Go to the graduation. Years from now, she will literally forget all the heartache she put you through, but she will remember if you weren’t there for her graduation.

What you should do is call the cops on the 20 year old for molesting an underage girl, your daughter. It is a Social Crime. Tell her that once she turns 18, it has nothing to do with her anymore, but it does have to do with the State law and protecting all the other naïve girls he WILL go after.

She will throw a fit first, of course. Say, “You can be mad”, and keep silent and calm while she has her tantrum.

Then let her “go” after her birthday. She will return one day, if only for $$.