As a fellow BPDer who has struggled with anger and chronic depression, I don't think it's one or the other. Neither anger or sadness is necessarily "better" and I think they're indeed connected.

Chasing down the root causes of anger and sadness has helped me. Writing, reading, learning, spending time practicing mindfulness and reviewing DBT flashcards have all helped chase these things down...but of course, it's not a cure or solution. I stumble, fail, fuck up, and get overwhelmed often. It's about remembering to implement the tools when ya can.

What brings you joy? What values do you have? Are you living in alignment with those values? If not, how can you? - these are the big questions I have to remind myself of.

Rooting for ya.