Family bombshell

Hi I just need some advice. I’m 20 and live with my parents and have always had an amazing relationship with them. Recently my mum received screenshots from a 17 year old girl showing that my dad had been trying to sleep with her. I feel disgusting and betrayed by this and he is still refusing to admit it, even though my mum has actually spoken on the phone to the girl involved so it’s definitely true. What’s even worse is that I found the girl on facebook and she has four mutual friends with me.

I still haven’t spoken to my father about this, the truth is I feel sick and I don’t see myself being able to move forward with any kind of relationship with him until he is honest, but he is still trying to cover it up. They are getting a divorce and within a week he has already moved out and is blaming the divorce on her. He is saying that he has to leave because she doesn’t trust him and he’s not happy in a relationship where his wife doesn’t trust him. He has always gotten angry every time my mum has become suspicious when things don’t add up, and I think he has been manipulating her for their entire marriage.

I just want to know in this situation is it acceptable for me to sever the relationship with him? He has always been the perfect father, we have had arguments in the past but this is affecting me to much I saw a councillor. I feel sick as she is younger than me and a minor and he is in his fifties. I just don’t know how to talk to him anymore.