Hello, and welcome here! It sounds like you are stuck in quite a situation right now. I hope he is somewhat better after you deliver your child.
Readign what you said... .
... .looking back I realize that he slowly robbed me of my personal power (of course i let him) and now I have been reduced to spending my life trying to keep my footing on a slippery slope.
Unfortunately I can't seem to get over the resenent I feel and it is really corrosive to my soul. I feel lost. ... .
How do I reduce resentment so that I can stay in this marriage. How do I avoid losing myself while I am forced to tip toe around someone who is completely dysregulated.
My take on resentment is that it is a natural result from the way you've been treated--consider resentment to be a cue that perhaps you need to enforce some boundaries to better protect yourself. It is much easier to let go of resentment of things that you aren't having to live with anymore than of things going on right now.
The place to start is by realizing that you are not forced to tip toe around somebody, or what you are afraid they might do. You have better options.
If you haven't found them yet, the lessons have all sorts of good stuff for you (links in right sidebar ---->> >> ). I'd recommend you start with the workshop(s) on boundaries.