I have a BPD diagnosis too, though i see myself as being ‘in remission’ just now. Part of my problem has always been trusting others. I have to be able to trust to talk about issues, but when i try, my behaviour often goes/went OOC.
DBT is a form of CBT. From my own experience i find working through CBT (and DBT) workbooks really helpful. They are especially empowering because i don’t need to speak to others about my issues, not until it feels safe to do so. I won’t give any names of books here, it’s probably not appropriate, but there are a lot out there. I would suggest having a search around and finding 1 or 2 that make sense to you, and trying to go through them gently, sharing where and when you feel safe to do so. As you find things that help you, you can add them to your toolkit maybe?