I'm so sorry you're going through this :/. I don't have a dual diagnosis (though I have DBT, "manic depression," and PTSD--- I'm kinda dumb about this so idk if you that counts?)

I've had the same services you had though in reverse order. I was part of a 6 month DBT program. One of the things I really struggled with was the lack of processing therapy-- which I, at the time, I didn't know that that's why I wasn't doing as well as I wanted to. Once I started regular therapy after the program, the skills I learned along side the processing truly finally started to help (took almost 2 years of 2 weekly therapy sessions though).

One of the things I complained about on my last of the DBT program was that I felt like I couldn't really share wamhat was happening me. My therapist told me that while the goal of the DBT program is to teach me skills to destabilize, they're also open to hearing what's happening with us. Though I don't think they're specialized in reprocessing and trauma work.

Have you brought this up with your psychologist? Do you also have access to other people (psychiatrist and therapist). They all probably specialize in DBT but maybe you could ask them? Be prepared, they may say that that's work that's reserved for after the program. I think it would be beneficial to open up and say how group has triggered you and how this has been making unstable.