How can I help a pessimistic person who seems unwilling to accept help and refuses to take medication or seek treatment?

I have been very anxious and worried lately.

I have been dating for 7 months with my boyfriend. We're both young, I gonna finish the high school in next year and he will finish this year.

he has been fighting with depression for some years and in the start he went to a psychologist, which was not suitable and on the first day he was informed that he had depression and that he should take medication. Because of that, he stopped the treatment and never went back.

When we started dating, I had already realized that he was discouraged and had low self-esteem, but I didn't know that the hole was so deep.

Three months ago, he tried to suicide but gave up because of the method. Two days later, he planned everything, and this time, he told me, he said he didn't intend to keep going with life that day and after a lot of talking I managed to convince him not to do it, he undid the things he had prepared to do it, and this time, he thought I had saved him, but wasn't the case, since when he stepped home, the will returned. After that, we had become much closer and I start pay more attention to him.

Three weeks passed and he told me he was going to try it again, that he couldn't take it anymore and that things would get better for everyone if he died. (A few days before that, his father was putting a lot of pressure on him, and started chasing him in search of an answer to my boyfriend's distance from him and the way he had been acting). That day I broke down, cried a lot and spent the whole day exchanging long texts with him trying to convince him to stay. And after a lot of anxiety and trying, I managed to. It's been about two months since this happened and he says he promised himself that he won't do anything because of me, and that even without strength, he will try to make me happy.

Even after that, I still worry daily, because he says that everything keeps getting worse. He have insomnia and doesn't sleep well, He lives with a mother who appears to have mental disorders and has a father who live in other place, who is not bad, but does not understand him.

He refuses to undergo treatment, he refuses to take medication and is very stubborn in his pessimistic viewpoint. He is very interested in suicide and consumes a lot of content about suicide, such as books, documents, letters, and works on general about pessimistic and suicidal philosophers. He's very stubborn and closed off, his mind finding comfort in misfortune and refusing to leave it. He's trapped himself in a bubble of self-loathing and doesn't seem willing to leave. He no longer feels pleasure in talking to anyone or doing anything. I really want to help him but I don't know how. I try my best to show him how much I love him and try to change his point of view, but it seems like he doesn't want to give an opening.

I love him and he loves me, we only have each other and I refuse to give up on him. I'm the only light he has and I need to make that count. I'm afraid of how things will go next year. Since he's going to college and will probably start working. Because of school and I have strict parents, it will be harder for us to see each other. And what worries me most is how we're going to keep in touch. Even though we have internet, as I said, talking isn't easy for him and I don't want to tire him out with text messages, plus I'm also terrible at expressing myself and communicating.

Because of this, I'm afraid I won't be able to help him as I would like.

I can't loose him, and I can't let him deeper on depression. How can I help him? How can I change the way he see himself? How can I make him notice that he deserves to be happy?