The fact you feel bad about it is enough.
this kind of guilt is even harder to process because it can feel near impossible to talk about. it's already difficult enough to reminisce. i'm sure when you were in that life, you didnt have the chance to take a step back and talk with friends or family about these feelings. and because it's criminal activity, there is extra incentive to keep it to yourself. i really feel for you and i see the pain you're going through.
is there anyone close to you who has gone through similar things who is willing to talk with you about it? maybe a friend or relative? i'm sure most people who live that way are just as unsettled and guilty, even if they don't know how to express it. if conversing with sympathetic souls is too difficult, i suggest journaling. it doesn't have to be good writing. you just need to get your thoughts on the page and out of your head. best wishes.
I used to be a dark occultist, unironically trying to bring the world to its end… Not only it wasn't that easy to process after the realisation of my wrongs, but I had to rewrite my whole way of living.
Tbh if you're able to withstand your old ways, avoid them and change yourself, it's already more or less considered as redemption, both in religious and social meanings. Feeling despaired wont get you to change things to better. If you did bad things to people, do good now. Consider volunteering. Plant a tree. If despair has crushed you to the point where you can't do anything, you absolutely have the right to heal that. If not for yourself, then for others, to whom you can lend a hand.
Anyways, I feel for ya. Past is a heavy thing.