Am I over reacting??

Am I over reacting here? My boyfriend/father of my three children was sexting with another woman. He said nothing more happened and that he would work on our relationship. Hes still friends with her on Facebook, she just posted a photo of her wearing a skirt, literally just a photo of her skirt and legs and he commented "haha you look like a girl"

In my opinion he should have deleted her off his Facebook anyway, but commenting on a post where she Is clearly fishing for attention is just bs. He obviously knows I can see it too, he doesn't care about my feelings right?

Also not blaming the woman, my boyfriend should have had a bit more backbone than to send a dick pic as soon as someone flirts with him... Is it blowing things out of proportion to break up with him over this?