Called me a bitch?

So my SO and I were casually talking about this girl we went to school with having a certain hairstyle and he was like she probably copied this other girl i went to school with. So i was interested and i wanted to see who he was talking about to see if i knew her. And i was creeping on her Instagram page and he was like oh you found her? That was quick? Then I noticed he liked her selfie but i noticed him and my cousin both liked it. I said " aww cute you and my cousin liked the same picture." (He met my cousin because of us dating so I thought it was funny how they were both following her) anyway, I didn't say it mean or anything. And he looked at me and goes "You're such a bitch. You're all of the worst parts of a girlfriend." WHAT THE FUCK. Like I didn't even do anything to him. And honestly I'm the best he's ever had. I don't mean that in a bitchy way.. but he's been cheated on and he has cheated. He's been my first everything. I don't think I deserved that.

I just wanted to see if i knew her because we had alot of common followers. I didn't go looking for dirt or anything. I was just curious. I hid the rude comment. I guess I'm younger so i said creeping instead of being curious. Guys I don't have anyone i can personally talk to right now. But i don't think he's cheating.