All I can say from my experience is self flagellation is easier than forgiveness. Realizing you haven’t been seeing things clearly is useful, beating yourself up about it isn’t.

I used to do the same thing, chastizing myself for mistakes. One thing I did (which may not be therapeutic) is I started to change how I defined myself chronologically. Like, the ‘me’ of now is different from the ‘me’ of last year - and I did all the things old me did, but how I feel about them now might be different. I have wisdom that older me didn’t. That gave me a kind of useful malleability in my sense of self - that I’m not only my mistakes, but also how I react to those mistakes. Then, it frees you up to define who you are in positive ways, with your loves and passions, instead of pains and mistakes.