I didn't do DBT therapy, but I have a DBT workbook that I find helps with these kind of feelings. I know what you mean about the habitual suicidal feelings. I think it's important to try to learn another reaction to these bad feelings. In my experience it can take time, and some deliberate effort (hence I find the workbook helpful). My T and I also worked on flashcards for these times, which is part of schema therapy. Eventually, it can become habitual to think through the things that are on the flashcards.