So far as I can find (and I have searched diligently) there is nothing in the scripture that directly addresses Yahuwah's attitude toward the specific subject of suicide or the consequences of such an action. I have been told the same thing you have by people who should have known better (which I am sure is your case also) but apparently didn't. This is one of the subjects for which I have done a lot of searching in the scripture and I have some answers that may satisfy your question.
Concerning death as addressed in the scripture, there are several occurrences of otherwise healthy people who made statements concerning a desire to die, such as found in Yonah [Jonah] 4:3, 8, but it was always desired that death come by someone else's hand. Yahuwah had something to say to Yonah about his desire and the reason for it, and what He had to say did not reflect kindly on Yonah. As a matter of fact, it kind of made him look like a pouting child who had not gotten his way, so he wanted to take his ball and go home. (Read the fourth chapter of Yonah.)
The only occasions that I can find that deal with any thing that can be considered to be cases of suicide are the deaths of King Sha'uwl [Saul] and his armorbearer, the death of Shimshown [Samson], who pulled the temple down on top of himself and many Pelishtiy (Philistines), Zimri, the king of Yisra'el who burned his house down around himself, and of course the most famous suicide of all, Yahudah, the man of the city (Judas Iscariot), who betrayed our Master, then hanged himself after the arrest of Yahushua. There may be more cases that I have overlooked.
The death of King Sha'uwl was accomplished by his own hand in that he deliberately fell on his own sword (which could technically be considered suicide even though he was apparently mortally wounded and was afraid that the Pelishtiy would find him still alive and abuse him before he died). But, he fell on his sword only after his armorbearer refused to kill him (See 2 Shemwu'el [Samuel] 31 - Sha'uwl's death is the fulfillment of the word of Yahuwah). Sha'uwl's armor bearer also fell on his sword (and since there is no mention of him being wounded that can probably be considered as suicide), but there is no mention of how these acts were looked upon by Yahuwah.
Physical death in general does not appear to concern Yahuwah. (Maybe He knows something about physical death that we don't understand or that we refuse to see?) He uses death throughout the scripture as a means of getting the attention of the people who are supposed to be His children. Sometimes it is the death of an individual (as punishment or as an example to others) and sometimes the death of tens of thousands for their sins.
Most people in the scripture who were aware of their impending deaths were fearful. Some attempted to put it off as long as possible. (See 1 Shemwu'el [Samuel] 28:19-20 and YashaYahuw [Isaiah] 38:1-3, for examples)
The individual deaths of many of the Yahudiym [Jews] was of no seeming consequence, as long as the nation of Yisra'el was kept intact for the purposes of Yahuwah and He ensured that certain individuals remained alive as His ministers. No matter how many individuals died or were killed, He always maintains a certain number in reserve. So far as the foreign nations [goy, Gentile, or heathen] were concerned, Yahuwah most of the time instructed the Yisra'eliym to completely annihilate them when they met in battle, sometimes even down to their flocks of domestic animals. The failure to do this is as instructed by Yahuwah is what caused Sha'uwl to be removed from his kingship and is one of the things that is still causing the people of Yisra'el trouble today.
This makes perfect sense when you think about it. The only people who had a seeming immunity to death were certain people who were doing the will of Yahuwah, and that immunity lasted only until the appointed tasks were complete (such as Mosheh [Moses]). At the time of the writing of the Ibriy (Hebrew) Scripture, the only people who knew Yahuwah were the people of Yisra'el, so they could be the only ones who could be intentionally doing His will.
Every death that is reported in the scripture that I have been able to find (with the exception of those mentioned above) is caused by an agency other than the hand of the person who died. People were killed in war, by objects falling on them, by the ground opening up and swallowing them, by murder, by wild animals, dying from old age, etc. Just about every way a person can die is shown in the scripture.
(Ecclesiastes 12:1-7) Remember now your Creator in the days of your youth while the evil days do not come, nor the years draw near, when you shall say, I have no pleasure in them 2 while the sun, or the light, or the moon, or the stars, are not darkened, nor the clouds return after the rain. 3 In the day when the keepers of the house shall tremble and the strong men shall bow themselves and the grinders cease because they are few and those that look out of the windows are darkened, 4 and the doors shall be shut in the streets, when the sound of the grinding is low, and he shall rise up at the voice of the bird and all the daughters of music shall be brought low. 5 Also when they shall be afraid of that which is high and fears shall be in the way and the almond tree may not blossom and the grasshopper shall be a burden and desire shall fail because man goes to his long home. And the mourners go about the streets 6 or ever the silver cord is loosed or the golden bowl is broken or the pitcher is broken at the fountain or the wheel broken at the cistern. 7 Then shall the dust return to the earth as it was and the spirit shall return to Elohiym who gave it.
In the preceding passage, which specifically deals with man's death, it can be seen that the spirit of man is given by Eloah (verse seven). The word elohiym is translated as "God" in most English versions while it is actually a plural word that means "mighty one/s." Elohiym is called the Creator in verse one and the Creation by the Elohiym is through the power of Yahuwah, who is THE MIGHTIEST OF ALL.
Ecclesiastes 12:13 - Let us hear the conclusion of the whole matter. Fear Elohiym and keep His commandments, for this is the whole duty of man.
Based on the preceding information I believe that the life of the individual is a gift from Yahuwah, to be used to further His plan and in accordance with His will (obedience). To end that life by your own hand is therefore to reject the gift of our Eloah, whose name is Yahuwah.
The deliberate and unlawful taking of a human life is murder, so the taking of your own life is murder, even though it is yourself that you are murdering. Based on Ecclesiastes 12:7 your life is not yours but Yahuwah's. That means that to take that life, which does not belong to you, is unlawful under the laws of man.
We can also see that murder is not acceptable in Yahuwah's law.
Shemot (Exodus) 20:13 - You shall not commit murder.
Yahuwah has made statements concerning the deaths of individuals, as is shown in passages such as Psalms 116:15 and Yechezq'el [Ezekiel] 33:11 (Below).
Psalms 116:15 Precious in the sight of the Yahuwah is the death of his saints.
Yechezq'el 33:11 Say to them, "As I live," 'said the Sovereign Yahuwah," "I have no pleasure in the death of the wicked but that the wicked turn from his way and live. You turn, you turn from your evil ways, for why will you die, O house of Yisra'el [Israel]?"
Note that He welcomes the death of those who are in obedience (called His saints). If you disobey Shemot 20:13 you are not in obedience to Him and therefore He does not look at your death as precious. You become one who is disobedient and lawless which can be equated with wickedness and evil, so He does not desire that you die before you turn from those ways. But by then, if you suicide, it is too late. The deed that made you wicked is done and cannot be reversed. The death that now awaits is the death that He will provide.
Do those who commit self-murder go to "hell?" To answer that, we must first define "hell."
Hell in the Ibriy scripture is she'owl, or the abode of the dead (Greek haides, English hades). It is NOT the grave. Prior to the sacrifice of the Anointed (the Messiah, the Christ), which brought in the New Law, all people who died went to some level of she'owl. There is much that we don't know about this place, but it seems that there are many levels, and the level where someone goes is determined by their actions in life. The poor beggar El'azar (Lazarus) went to the bosom of Abraham, while the rich man went much lower. (Apparently the lower you go the hotter it gets. In the lowest level is where certain messengers are chained awaiting the day of judgment.) This story was told by Yahushua so it demonstrates the concept told about in the paper titled "Hell" on my page. Now how about that hellfire that Yahushua spoke of? Well, He never said hellfire, but that is the way it was translated and therefore has been accepted for centuries. Read that paper for more detail.
Do people still go to "hell" (she'owl) today?
Those who are not in obedience to Yahuwah at their death. This can be seen throughout the Greek scripture too.
Dealing specifically with murder, Sha'uwl (Paul) states in Galates (Galatians) 5:19-21 that murder is one of the works of the flesh and that those who do these things shall not inherit the kingdom of Yahuwah. If you are not eligible to inherit the kingdom when you die, you have to go somewhere else, and the only other place I know of is she'owl. He says in 1 Timotheos (Timothy) 1:9-10 that the law (Shemot 20:13) is made for those who need it, including murderers and others who resist sound doctrine. The delegate Keph (Peter) states that none of us should suffer as a murderer, and then the delegate Yahuchanan (John) defines murder even more narrowly as hatred of your brother.
So now you know as much about it as I do, and maybe you already knew this much anyway. I pray that I have been of some help in answering your question. Let me know.
In Yahushua's Love and Service,