Is self forgiveness ethical if the damage can't be undone and the other person is damaged for life? + another question

I tried to post this in r/SeriousConversation but it hasn't been approved in the 48 hours since I tried, so sorry if this is the wrong sub.

I truly struggle with the idea of self forgiveness. Some people talk about it as a way of finding peace, but it seems unethical to me in certain contexts. The snark of 'well at least you forgave yourself' seems valid in some situations. I'm thinking of selfish actions that lead to lasting trauma on the receiving end. It just seems wrong to say 'they can't get over it, but I'm going to let myself move on and stop beating myself up,' even if the offender has changed or regrets the actions. I'd like to be convinced otherwise, but I don't see it happening. ​

The second question is, I've heard the argument that apologizing because you feel guilty is selfish, but isn't that the only true apology? It seems the options are don't apologize, apologize without feeling guilty, and apologize because you feel guilty. The last one seems the only 'good' choice. Am I missing something? ​I'm not talking about actions vs words, I just mean the reason behind them.