Can people change?

I was in a bad relationship for 3 years. My boyfriend was just very immature and selfish. He kissed someone else our first year dating because we were never physical with each other, not an excuse just sharing the back story. Whenever things werent great with us I saw his attention go else where. He wasn’t mature enough to actually commit to someone. but while there were bad times we also had really great ones. I do believe he is a good guy.. We’ve been broken up for a while now, and I still do love him. And he’s recently been reaching out telling me how he’s grown as a person and is now holding his own job and how he cries over the fact that he didn’t see how great I was for him and all that. I guess I’m just asking for experience. Have any of you gotten back together with someone after serious hurt, and they actually did change? I know all the bad stories, once a cheater always a cheater, and all that. But I’m just confused and want to hear stories. And if so, how did you get the bad thoughts from before out of your head? Thanks ladies!