I need your help ladies!

So a few days ago i went through my husbands phone, (i know, terrible of me) but he has had trouble with cheating in the past. I went through his messenger and found a girl he had slept with while we were together, and during this particular night he hadn’t answered me for hours, so i knew he was cheating. I found it and read the messages between him and this girl. Apparently they did something neither one of them has done before..and this situation is really bothering me. How do i bring it up? Do i bring it up? what should i say? Thank you ladies! Any judgment please bring somewhere else. Spread love and happiness!❤️❤️