It's a bit of a MN cliche, but I could have written your post, OP, with slight adjustments for figures, i.e. years wasted in a crap marriage.
It's normal to feel a bit shrivelled up after such experiences. However, you are the boss now, and you get to choose your next chapter, so make it a colourful, brilliant, hilarious one as a massive antidote to what you've endured. Do you have dependent DC? If not, that gives you vast scope. If you do, you can still pack in lots of good me-things around their needs.
It can really help to get away from your usual environment for a while. Do you have the means (and Covid-era allowances) to take a trip for a few weeks? Lots of travel companies do active holidays for families. Time away can help pull you out of a rut.
Personally, I wasn't able to do this at the time as I was dealing with a shitful XH, all the hoarded crap he left behind, a distressed DD and a recently bereaved DF with dementia. What helped me was going back to the music I loved before I met XH all the '90s acid jazz and crazy-alegria Brazilian music of my big South American trips. It started to bring back the person I used to be, and reminded me that life was not just drudgery, resignation and walking on eggshells it was dancing, singing, learning a new langauge and seeing amazing places, too.
You feel damaged now, but that damage can be repaired.
As a simple start, a bunch of us are doing Move: 30 Days of Yoga with Adriene, a free beginners' program to get you stretching -- and stretching is scientifically proven to make us happier. Come over to the Yoga board and join us. It starts on Jan 1.