How do you move past guilt and shame for past mistakes?

[Dlavjr]

An ex girlfriend recently has been trying to get back in touch with me. My relationship with this girl was very toxic and she ended up cheating on me. The person that I was during this time was terrible. I was mean, selfish, and hurt a lot of people during that time. I've made the firm decision with myself that I will, under no circumstances, be seeing her again. 

However, with all of these thoughts and emotions arising, I'm feeling a lot of shame and guilt for who I was during the 2 1/2 years I was with her, and I don't know how to forgive myself or move on. 

[Harlen Kelly]

@Dlavjr Treat the thoughts about shame and how awful you were that arise as objects in consciousness, without attaching any special importance to the thoughts. 

The problem is not the shameful thoughts, the problem is your attachment to those thoughts, you are getting lost in the content of your mind. Just observe, and that's about it.