Hi Emma101 and welcome to the board! There are a lot of people here who can relate to your situation with your brother and who can offer support and soft place when you need/want it.
It is hurtful when a family member knows how to hurt us so deeply. It sounds like your brother knows just what all your most sensitive areas are and just how to poke at them. The thing is, what he says about you and to you (about your character, your skills, etc) have more to do with him than anything to do with you. When a person with BPD (pwBPD) is as dysregulated as he gets they can't really see you, they are seeing their own self, fears, insecurities projected on you. Their own feelings define reality for them. Here is a link to a discussion about
ProjectionAn excerpt from the article:
Projection is a defense mechanism, operating unconsciously, in which what is emotionally unacceptable in the self is unconsciously rejected and attributed (projected) to others. Projection is denying one's own unpleasant traits, behaviors, or feelings by attributing them, often in an accusing way, to someone else.
I gave you this link to start because I think it may help you detach from the hurtful comments he makes. Not that they won't still hurt, but hopefully you will feel less devastated by what he says as you learn to remind yourself over and over that what he says is a reflection of his own self and has nothing to do with you. My mother was great at projecting her own insecurities and irrational fears on me. Projection was the first thing I learned about BPD behaviors and it helped me quite a bit to stop additional hurts from building. I hope this will help you as well. There are lots of other articles that you might find helpful as well, I just figured I would start here.
learning about the various behaviors common to BPD is not so much to help or even understand your brother, but more to protect yourself by depersonalizing his behaviors as much as possible.
Emma, I am glad you are reaching out for and I really believe this is the best place to land for support and learning. I see you already found a thread started by someone else with a BPD sibling. There are several others currently posting who deal with siblings, plus you have a lot of us who had/have uBPD (undiagnosed) or BPD parents, etc. We all get it and can help you process things.