Fiancé cheated on me with a 16 year old girl

He’s 22. Is it just me or is that like gross ?? We have a 1 year old and I’m 23 weeks pregnant with our second. I’m disgusted. I don’t know what all they did but it doesn’t matter. I want to throw up. Him and our son are asleep and I’m about to get my son and go. He’s a great dad but obviously isn’t great to me. Pray for me 🤞🏻