Hi Adam,
Like Chris, I also have had such thoughts. And I nursed the suicidal thought/plan for a long time because I was quite angry at conditions on the planet even though my conditions were quite comfortable. Social conditions on the planet and my relative impotence to change them pissed me off and when I wasn't pissed about that I was kind of asking non-stop, "Why is it like this?" and from a very depressed mind (I exercised a lot and removed sugars and caffeine as somewhat stablizing countermeasures during that time; this part of my life was before the advent of pharmaceuticals and I don't know how those work, but people may be able to help you evaluate that option). At one point then I began to design a system of suicide that would impact people the least. I lived very remotely (in a very beautiful remote part of the world without many people! I laugh and think, "Wow, I was putting a barrel in the mouth there of all places? That's ridiculous." It was such a beautiful, calm place and I was free to stay there. How amazing that I was creating such a nutty thought all the time, "Don't want to be here, don't want to be here."
If I tell my parents I am suicidal they don't take it serious anymore after all we have gone through,
So it can be very hard to change habitual thinking when one is living in the habitual place wherein one built the mental habits. It takes very, very regular, dedicated countermeasures of practice to undo a habit in the location it was formed. And even if you moved, it still takes very, very dedicated countermeasures to start building new mental pathways and the old mental pathways take a good while to fade. So if there are suicidal thoughts for 15 years, they can still be there 15 years later, but just without any potency, just like brief silent movie clips.
So if you are ready to take yourself on a mental training experience before you die of any means, I highly recommend, that in addition to traditional help, you start training in friendliness for yourself, your own condition as living animal in this world, right now and have every mental moment directed in kindliness and gratitude. Here is one such training teaching:
https://www.youtube.com/watch?v=uirHkgN-pao Else if you are better in a theistic frame, please consider a potent mental re-training tool in that tradition, such as gratitude and "This, too, is God" and relaxing with that. Gratitude is hugely helpful practice and can build metta (friendliness, welcome, kindness) -- even just commit to such mental experiment for two weeks, but every moment the mind is gently told to go to its good practice. Just two pure weeks of experiment.
Clearly, if one has the power to end one's life one has the power to do two weeks immerse in moment-to-moment re-focusing the mind to see things and people with gratitude, kindness, compassion for other people's conditions-actions. When one is so low, it is also I think the most ripe time for such a sincere practice effort.
I would also like to caution you that the suicidal act can be mentally very painful. A friend who did not succeed a few years back (and is very healthy today via his own theistic practice) told me about how time slowed and how very hellish his trip into dying was, the mental anguish all the way down; instead of escaping these thoughts and painful existence, these horrible states seemed to be reifying around him. Being brought back to life it seems he saw he had a lot more choice in his thinking and how he uses his heart-mind.
I see things in terms of cause and effect: if I plant daisy seeds, I likely get the daisy flower consequences. To plant suicide, puts in motion new consequences which are related to their cause. I have no reason to think the consequences of suicidal act would not then also put in motion more painful seeds, and my friend attested to this (up paragraph). From your mental state now, it may be very hard for you to reason this or anything but "wanting out". I hope you give your self a two-week experiment in sincerely retraining the mind positively, suffusively.
I wish you the best, Adam, and thank you for sharing this. A lot of beings experience the desire to not be here. One can effect such a death, but one can also train one's mind-heart to being here well among others despite relative conditions. I don't know what your conditions are, though and what your mind is having to re-train through. For example, when children are abused, their brains and brain stems (I think) have higher vigilance/faster triggers and so one should know if one is also have to train the old "reptilian brain" (brain stem brain) in addition to the big new brain. The countermeasure for physical violence in childhood (or war zone) may also include a lot of physical therapy and learning about how the body is very primed for reactivity and that executive function (self-reflective and decision-making capacity) needs to know it is dealing with a very reactive animal (the brain stem). I hope this makes sense.