There are some line that people shouldn't cross if you want a healthy relationship, some include
1. Blackmailing and betrayal
2. Murder attempt or attempt at harm
3. Being a liar and sow a seed of conflict
4. Blatant show of disrespect and personal attack
She already cross some of em, I don't get why she deserve any better just because "muh past", to have a horrible past doesn't mean you get a free pass at inflicting your pain to the other