I just want opinions.

My sister isn't the greatest mom per say, since she always leaves him up to our mother to take care of him. My husband despises it and her in general. Today we seen her after a few weeks while we were at my mothers house (she was picking up her son). He made two snarky comments "Atleast you'll get a break" & "Since you're mom number 2". After we left I told him no matter how much you dont like her, atleast keep your comments to yourself. He goes I will never say anything to your family again then and got butt hurt I was upset about it. I never make comments towards his side of the family. He said well your mom is my mom now and your sister is my sister so I think I should be able to. Am I wrong for getting upset he made comments out loud?