I don’t know what to think

I have this small group of friends that live in other states. We are a pretty close group even though we have never met in person. Consists of 3 women and 2 men. We vary in age but no one is less than 25. Our male friend confessed last night that he met someone on line that lives in another country. He’s already engaged to another woman in South America. I was disappointed to hear that he was essentially cheating on his “fiancé”. He then admits that this other woman is 18yrs old. He’s 46. It made me so sick to my stomach. It’s not illegal but it’s just so wrong in so many ways. Myself and another female friend kind of laid into him about it and he knows it’s screwed up but he was legitimately trying to justify it. I have a son that is closer to this girls age than our friend is. I’d be LIVID if a 40+ yr old was trying to have a relationship with my son at 18. He’s definitely gotten a mouthful from us about it but I want someone else’s opinion on the outside.

How would you feel? What would you think? Would you be accepting of this? Would you stop being friends with this person?