Would you be mad?

I've been with my boyfriend for 2 years, we are expecting a son in November. Well my boyfriend has always made "joking" comments about my aunt just saying things like "heyy" she's "hot " i wonder if she puts out.. just stupid shit, yesterday we went to the carnival with her and he walked with her the whole time talking, i blew it off but today she post a picture on facebook and said make up free summer and he commented "heyy whats up 😉" and said I'm over reacting it was just a joke with my aunt. mind you my aunt is much skinner, nice fake boobs a beautiful women who also has a history of having sex with my mom's ex husband so why wouldn't she do it to me and the way he acts..