Am I right in telling her to leave me alone?

My ex sisterinlaw/best friend slept with my fiancee awhile back. She was still married to my brother at the time, but says that since they were "seperated", it's not cheating. And she also doesn't think she didn't do anything wrong, nor that her choice of person was wrong as well. She has said so herself that she doesn't feel bad for what she did and that there's no reason to apologize.

After I found out and my fiancee and I decided to work it out since we have a son and are going through counseling, she prank called me for like a week, called the cops on me for stupid things, and we even think she tried to pull the break line on my care. She is very manipulative and made people take her side saying horrible things about me.

I made it very clear to her that I never wanted to talk to her or be her friend ever again. I have to see her like once a month since her daughter is my niece. But other than that I ignore her when I do see her.

She has since tried to talk to my fiancee and wants to be friends with us again since all her friends are only online. She even goes as far as to send me a text saying Happy Mother's Day.

Is it wrong for me to tell to leave me alone, it's like she isn't getting the picture. I feel as if she's trying to make me feel guilty, but I don't.