it took me many many years to finally see that the loudest victims i have dealt with were (and are) actually the worst abusers. They are just giving themself the excuse to treat everyone like shit and manipulate people, and there's no need to apologize or take any responsibility for such behavior -after all, they're the victims.
The adage "Hurt people hurt people." is true in a lot of ways. It's important to have compassion for those people and more important to set clear boundaries.