The thing that sticks out to me here is that he's 30, and you're not even legally old enough to drink. That alone tells me that he has issues of his own; mentally healthy 30-year-olds don't try to date people so much younger than they are. I'm not saying you didn't also do things wrong in the relationship or hurt him, but honestly, he should never have been dating someone so much younger than him at the very least so he does have some culpability here.
There's also the fact that he tells you to he wants you to leave him alone forever, and yet you can tell that he's in pain and he tells you his life will be "empty" without you. That's extremely manipulative behavior on his part. He has a right to ask you not to contact him if he so chooses. Everyone has the right to end relationships that aren't healthy for them. But the way he chose to do it, making it so you knew that he was in pain, crying in front of you, telling you how empty his life would be, that's not how someone goes about terminating a relationship if they really just want a clean break.
Also, not to harp on this, but you're nineteen. Lots of 19-year-olds make bad decisions in relationships because they're young and lack experience in dating, even when they don't have BPD. That's completely normal. I know it doesn't make the pain go away, right away, but someday, I promise you, it will. Lots of people, with BPD and without it, have cheated, been cheated on, and survived. Your relationship with your current boyfriend may or may not survive this (I would encourage honesty about what happened, and telling him you want to work on things if he's willing to give you a second chance; accept that he may not, but also, go in with an open mind and accept that he may be willing to work on things with you).
But I promise, even if it doesn't seem like it, you will find someone who loves you. You are not "destined" to hurt people. Getting perspective into your diagnosis at a young age is a blessing because it means you can start working on the things necessary for you to maintain a healthy relationship, figuring out what those things are. Continue with treatment if you're in it already; if you're not in it and it's an option for you, look into it. Someone else mentioned DBT, and that's always going to be a good option for people with BPD.
You have so much time ahead of you and you sound like you have a good heart. I have faith you'll find someone who loves you, whether that ends up being your current boyfriend or not. You have the double whammy right now of being young and having BPD, two things that can both make life seem more hopeless than it is. But it's not.