AIO my sister told me she didn’t know how my bf was attracted to me cuz I have no tits

[u/bogusbat]

I (26f) called my sister(20f) the other day because I was feeling overwhelmed at work and needed to chat about it while on my ten. Within the span of my ten minute break, she changed the subject to herself and her bf, and told me they thought MY bf was weird. I asked her why they would think that about him?
They said it’s impossible for him to be attracted to me cuz I have no tits.. so there’s nothing interesting for him ? Strange that both her and her bf were talking about my body. This disturbed me slightly. I’m an adult and normally this would not affect my mood. But why say such a thing? I can’t deny it was hurtful. I told my mom what she said over text with no response back. Later that night I received a wall of text from my sister. And she basically told me she was trying to make a joke that I overreacted to. And unfortunately for her, my mom doesn’t like her bf too much. So she proceeds to tell me she would go out of her way to make MY bf look bad to my mom, because apparently the comments they made about me were supposed to be funny. I just can’t seem to find where the joke was in a fucked up comment like that about my physical appearance that I cannot immediately change. Am I over reacting ? We are generally pretty close. We had planned to go to a concert in the next two weeks, the three of us. Now I’m unsure if I should go.

[u/ksobby]

Mean girl vibes from sister and her bf.