Big relationship mess!!

warning: long post
I've been in a relationship with this guy for three months. I really like him, we're both suffering from some pretty bad mental illness (borderline personality disorder, ptsd, depression) so it definitely makes things plenty complicated. i met him through tinder, so honestly- neither of us expected anything to come out of it. it was the summer and when summer was over, i moved to montreal for school and he moved to thunderbay. before he happened, i was hoping something would happen between my good friend and myself- who was also moving to montreal. those feelings hadnt fully subsided, and now im in a very sticky situation. my friend does have feelings for me, and yes, i also have feelings for him. my boyfriend feels threatened by him and gets upset whenever he is even brought up in conversation. he doesnt like when i spend time with him, even though he's one of my only friends in this new city. i think about breaking up with my boyfriend constantly, moreso when we're not physically together. he's going through a lot right now and myself and my family are the only good things he has right now. i feel like breaking up with him would be selfish and im afraid if i do it, he'll kill himself. im all he has, but it puts a lot of weight on me, too and im also sick, and i cant give him the support he needs right now. i really dont know what to do. thanks for reading this