Welcome, mynameisjonas. It's great that you're such a supportive and caring friend. I think it's great that you're looking for a way to help a friend in need, but I am a bit concerned that you've "diagnosed" your friend as having BPD. It's obvious from your description that your friend is experiencing significant life problems, but the symptoms can be from many things other than a personality disorder and the only person who can diagnose mental illness is a psychiatrist and/or PhD clinical psychologist. Please excuse me from making the assumption that you made this diagnosis if he has actually been to a psychiatrist who has given him the BPD diagnosis.

I think the way you can best support and gently guide your friend is having a conversation with him about how he sees his life going. Chances are he's aware on some level that things are beginning to unravel. Even if he harbors feelings that his current difficulties are everyone else's fault (ie. his ex girlfriend's perceived betrayal or his friend's abandoning him), he's bound to talk to you about how all of this has affected him negatively if you support and present yourself as interested and concerned about how much pain he seems to be in. He might even be open to seeking professional help to unravel and cope with these losses. The important thing is for you to listen and support, and then gently guide him toward seeking out help. If you've been in therapy, you can mention how helpful you found that experience to be. I've used that many times when assisting friends to seek out help. Nothing like a good friend admitting that they needed help and sought out theray to make the experience less mysterious or shameful for the other person. Good luck and I hope your friend recognizes and benefits from your compassionate approach to his difficulties!