This is bothering me so much

So I saw a picture in my boyfriends gallery and i saw this selfie of him and a girl. He told me that it was the past, and I believed him because of the date. He even told me her name. Yesterday my nosey ass decided to look her up on facebook. My mouth dropped as I saw this girl in a HIGH SCHOOL UNIFORM. Y’all. I was shook. I looked at him and said “this is recent?” And he says yes. When I tell you I was getting mad at him!! He admitted he slept with a 16 year old girl. She JUST turned 16. My boyfriend is 25 years old and turning 26 next month. He told me they used to “talk” but not in a sexual or flirtatious way. But wtf? I have a 17 year old sister and I think they had gotten along well, but to see what kind of intentions he had with a girl YOUNGER than her, a child 🤢🤢 I’m getting sick to my stomach guys. Am I crazy for thinking this way? I cant get out my head. I’ve ignored him for the past 12 hours because I can’t stand it.