I feel like I've said something wrong...

My mom and aunt were talking about her hair thinning and I cut in and said she could possibly have alopecia (in a none joking way) and she blew up on me, saying that I need to "shut the fuck up" because I always want to make everything a joke and I stated that I wasn't kidding and she goes "well, when I called you fat, you got mad as hell" but that was only because her and my dad made fun of me the entire time, even after I told them it was wrong and they didn't stop.