How to forgive yourself for past mistakes

During 2024-mid 2025 I got stuck in a pretty destructive cycle. Some years before that, I had healed from PTSD and got medicated for bipolar disorder, and was finally able to live a normal and healthy life. Before healing, I wasn't the best person, but I've moved on from that and forgiven myself, as I was very young and unwell. But in 2024, something changed. I ended up in a pretty bad mental state due to some life circumstances, and eventually developed an alcohol problem. I became a person I'm not proud of, and hardly recognize. I was completely delusional and unhinged. I was supposed to have healed, and I felt like I was back to the destructive person I had once moved away from. Last year, things got better and I see everything more clearly now. The problem is that I can't seem to forgive myself for how I acted. I ruined a lot of social relationships. It eats me up daily, probably because I'm ashamed of myself. The shame doesn't only affect me, but it's caused me to apologize to the same people over and over again. These people were barely in my life anymore, and the constant apologizing was probably a bad attempt at trying to rid myself of my guilt. It wasn't something they needed or wanted, because they had forgiven me and moved on before. I was just repeating the cycle over and over again. I've stopped apologizing now, because it doesn't serve anyone, but I can't shake my constant guilt. Now that we've upped my medication and my life circumstances are better, I'm a more pleasant person again, but I just can't forgive myself for some reason. Logically I have, but my feelings don't catch up. I was a really bad friend at the time.

It's late so this is all jumbled, I apologize. How can I really move on? How can I stop this cycle of self pity and guilt?