One of the rules of this board is to not tell posters to stay or leave a relationship. This is because people have different circumstances and so have to decide for themselves.
In your situation, I will try to give some perspective, as I am older than you are but I also was in college once
and I assume your BF is too.
I know that relationships are very real and intense - but also that young people in college are still figuring out a lot.
Even if your BF didn't have BPD, many college age students are just not fully emotionally mature yet. We know that brain development is still happening through the late teen years. Add a mental illness to this- your BF may just not be able to manage a longer term relationship.
So while I won't tell you to leave a relationship with him- he has decided to break up and is stonewalling. It's possible that this has nothing to do with you and is entirely what he wants to do. It would be better if he broke up in a more mature way than this- but this may be all he is capable of.
Breaking up, being stonewalled- that hurts but I think of all these experiences as part of learning about relationships, who we are, who we want to be with for keeps one day. It may not feel like this now- but I hope one day you will look back on this experience as part of that learning. However this turns out- there's a lot ahead of you and college is your time to learn and grow- so I hope you can turn your focus to that.
