BPD + PTSD in a relationship

hi, i posted this in the main love and relationships forum but did not recieve the feedback i was hoping for. i am in a very messy relationship. my boyfriend and i have been together for three months, i am all he has and we both have borderline personality disorder depression and he has very bad ptsd. he is new to his, and his life is currently in a big rut, mind you from what he's told me his life never sounded very great anyhow. i like to think i can deal with my bpd better, but both of us having it makes things very difficult. i think about leaving him a lot, for small reasons, like different outlooks on the future. i also feel very stuck, we are long distance currently and its difficult for me to remember how much he means to me. this is new to me because i have a habit of falling for guys on the other side of the world. i am overwhelmed by his constant need for validation, i am overwhelmed by him needing to call every few hours when im out with friends. i want to support him in this bad time, but i cant and i feel like if i broke up with him he would kill himself. this isnt an irrational worry, either. he has nobody else but me and my family. i dont want to make this any longer but there are so many more complications. i see a therapist regularly, i have a good support system and i have seen a psychiatrist . this is more than he has done and im worried for his well being