My fiance is liking womens fb pictures

We've been together 3 years and have a 3 month old daughter. I recently found out that he's liked his coworkers pictures on Facebook. She's standing on her own, in a small, tight, red dress with her breasts buldging out. Then i type in "photos liked by ___" and see quite a few good looking women. I feel so insecure in this relationship now. It feels like a betrayal and he's checking out other women. He says he just liked it because she used to be fat and lost alot of weight because her and her boyfriend broke up (so shes single) and its 'her' from 2 years ago that we fought over because i phoned him to work and they were both laughing so hard😐 he hates work and is normally so depressed there and hates everyone there. So he dug himself a bigger hole. I then said, so what about the other women you've liked? And he shit himself. He had no excuse. He said its nothing sexual and if its a nice picture he'll just like it and scroll on. But he doesn't like any of his male friends pictures?? He said when he was liking them, he thought "if Paula seen i liked these she would go crazy!". why like them then, if you know its wrong??

I finally let my guard down to a man and completely let him in, he knows everything about me, i gave birth and he watched it, I've gave my all. Everytime I read on mommy groups about their men doing this, i always used to think "my John would never do that", and scroll on smiling. & here I am...

My body feels like its burning, im red with anger and embarrassment.