Is it wrong of me for not wanting my daughter to hang out with my ex and his new girlfriend?

My daughter was 13 when i married my ex and when she turned 15 he started hating her. He never said anything nice to or about her. he has been my ex for about a year now and he just recently started dating a girl that was a close family friend of both of us.( i thought she was my friend!!). My daughter is 21 now and doesnt see anything wrong with hanging out with them. I do!! this girl was my so called friend up untill 2 days before she slept with my ex. even though he was my ex we still dated and slept together and talked about getting back together up to a month before this. my so called friend knew this and she started calling and texting him 1 month before they got together. i see it as betrayal and disloyallty by me grown daughter. am i crazy. i have seen some of my daughters emails talking about me being jealous (true, i still love the jerk) and them hanging out but not to let me know. please help answer this question before i blow up. is my daughter being disloyal and betraying me?