Am I a bitch??

So my fiancé bought some shirts and while I was on the couch reading a book to our daughter. My fiancé walked in the living room wearing the shirt. And he wanted my opinion on the new shirt. I was in the middle of reading when I told him I like the shirt and by accident without thinking said that it looks good but it shows his belly which I said it’s fine still looks good. My fiancé has a dad body Which I like. I don’t care even if he was 300 pounds. Anyway he freaked out and said are fucking serious you just called me fat. I told him I didn’t mean to that it just came out without thinking. Now he said he won’t wear that shirt and that he’s going on a diet. I feel bad. He’s very upset. Was I a bitch to say that?