AIO, about to go nuclear over a text my kid’s coach sent her.

So my (m35) kid's (13f) coach (60+m) sends messages on a group chat with her and her mother. I think it's weird and I expressed concern multiple times to my ex to no avail. Well yesterday he texted this on the group chat and I about lost my mind. Called him and screamed about how sick and inappropriate it was. He tried to say it was a joke and he was trying to "show her the color" He's said creepy things in the past but this in the most bold he's gotten. I'm about to report him to the director of the club and make something happen to prevent this perv from being around a bunch of little girls. I just want to make sure I'm not overreacting cause I feel like I want to k*ll him for trying to take advantage of my kif kid.