How do you struggle with your past?

I had an episode that completely and irrevocably changed my life. I don't want to go into detail in a public setting, but it was completely and irredeemably horrible what I did. The people I've spoken to tell me I'm not a monster, but I feel like one. I can't stop feeling like one. All I've been looking for was an excuse to justify what I did. I feel like a horrible person, I crossed a line that can never be uncrossed.

People tell me I need to be kind to myself. If you had done what I did, kindness would be the last thing on your mind. I don't believe I have any intrinsic worth. When I talk to friends or family, there's this nagging thought at the back of my head, "they would hate you if they knew what you did or who you really are". Again not going into details, the behavior was a single episode, but one time was one too many. I don't know how to cope with this. I've ruined my life. I feel like such a pig.