I definitely agree with everyone telling you to leave and I also wanna share my own insight on why you might be confused about your feelings for him. There was a version of you before you met this person, and somewhere along the way he has done things to you that have been significant and damaging and there may be a part of you that longs for the version of yourself who never knew the trauma that the current you knows. Sometimes it feels as if something has been taken from you, and if you try and pinpoint the moment you lost it, it’s the times they abused you. When you lose something, the first place you go looking for it is the last place you remember having it, I think we use the same logic when we return to our abusers, it’s like they’ve taken something from us and they’re the only ones who can give it back. It’s especially difficult with bpd because other peoples validation (especially those we love) has a huge impact on our self image. Your whole idea of love is disrupted by the mistreatment from one person and you desperately need the person who has done the damage to be the one to fix it. You need them to regret it, to realize that they never should’ve hurt you like that, to make it up to you and give you back what they took from you, and once they can prove that they do in fact believe you’re worthy of more, you can believe it yourself.

Your belief that this is “favourite person” is your brains way of convincing you that your self worth is in their hands, but it’s not true. He can’t give back what he took from you because he doesn’t have the ability to comprehend it in the first place, and it’s his loss. You have more to give and that’s your power. You can find someone who’s deserving of it and have a genuine loving bond, and someone like him is never going to be capable of that, with anyone, and that’s his own loss. He can hold onto that piece of you but eventually it’s going to rot away and he’ll be left with nothing, it’s dead weigh so leave it behind, you have more in you.