I know that this comment doesn't translate really to a solution for you, but can I just say how awesome it is that you didn't let yourself give up on DBT after the first time you were unable to complete it..?
I find lots of things are hard to attempt again if / after I perceive that I've failed previously... It's hard to put in words but I feel like there's a kind of subtle accumulative shame that can make it hard to show up again - it often prevents me from trying things (more often than I wish it did).
Its really reflective/thoughtful of you to consider that their (poor) responses may be fear-driven... BPD is so heavily stigmatised, it's so sad!
All I can really add beyond that is that I'm really sorry you're going through this, I can relate a little as I've been through similar (but different) situations... Sadly, I can't say that any of the outcomes I eventually got to actually felt "fair" in the end.
In my experience I learned that there is a lot of injustice in the world - some that can be called out, addressed and changed - most were in the category of the sort of injustice's that I was unable to influence or change, regardless of what I tried... As corny as it sounds, in both instances - acceptance (and making the most out of my circumstances, trying very intentionally and deliberately to notice good things, no matter how small they were) was where I ended up to help me cope.
Keep trying and please celebrate the fact that you keep trying! I hope things get easier/better soon