I made out with my ex-girlfriend turned friend and ruined our relationship. Twice.
Was it your call to end the relationship when you were dating?
I made the decision to end the relationship.
If you ended the relationship, but still made out with her after that, then maybe you made the wrong decision to break up with her. If you both still have feelings for each other, it would be a good idea to talk through this so you can truly find out what you both want to do.
We have already talked about this. She wants to remain friends, and I've ruined that by kissing her.
It seems like you have remorse for kissing her which is good, but you need to respect the boundaries she set. She told you that she just wants to be friends for now, and you need to treat her that way. If she wants to get back together, I'm sure she will let you know in time.