My husband ed our 5 month old!!?

Okay so my husband is a good dad but he does have a temper. He never gets violent or anything so Im wondering where this came from all the sudden. Last night my 5 month old woke up for a feeding and my husband got up with her. She ended up spitting up all over her pj's. So he was changing her clothes and her diaper and she was crying and straitening her legs making it hard. well he couldn't get the diaper on and so he swat her on the bare . She screamed!! And so I screamed at him and told him he disgusted me. He said oh it wont hurt her. I took away my daughter and finished myself. And we haven't talked since. It wasn't hard enough to even make her bum red but what infuriates me is that he did it out of anger. Am I wrong for being mad at him? Did I make too big a deal about this?