I Am a Victim of Emotional Abuse

My sisters ex boyfriend use to live in the same house as me.

He was mentally abusive.

Sometimes she talks about how badly he treated her. And how he was wrong to treat her that way.

And then I'll talk about stuff he has done to me. But when I try she defends him and says it's my fault maybe if I said something in a different way. Or done something differently he wouldn't have acted that way.