they ended up hurting each other
Honestly, when she was talking about a potential rebound, as a friend, that is what you should have talked about: does she believe this time would be better, and why? As a friend, you have no say in who she dates or not, but as a friend, you should help her to make the best possible decision.
Aside from that minor detail: I don't think you are the asshole here, or anybody involved, actually. This is more a case of a complicated history, and for one reason or another, now it boiled over. Things like that happen.
If you still value the friendship, then let a few days pass, then invite her to an in-person meeting. Start it with something you always liked to do together, following with a situation where you can talk privately. Then ask her about her feelings, wishes and worries first, actively listen, and consider what that means for the both of you. Can you help her wishes and diminish her fears without hurting yourself? And then take it from there, and good luck!
Aside from that minor detail: I don't think you are the asshole here, or anybody involved, actually. This is more a case of a complicated history, and for one reason or another, now it boiled over. Things like that happen.
If you still value the friendship, then let a few days pass, then invite her to an in-person meeting. Start it with something you always liked to do together, following with a situation where you can talk privately. Then ask her about her feelings, wishes and worries first, actively listen, and consider what that means for the both of you. Can you help her wishes and diminish her fears without hurting yourself? And then take it from there, and good luck!