<human>: Could you distill the essence of the text into 1-3 sentences?

Most of the time, the house consists of me [17], my mom [49], and my sister [19]. My sister has always been incredibly judgmental and nosy towards me (self-confidence issues and wants to appear better than me, I don't really care), and I can handle it when it's just the three of us. When her boyfriend comes over [19] it amplifies and I'm constantly being ganged up on and bullied. They judge me for ridiculous things, they're mean to my dog and yell at her and put their hands in her face, and I'd rather just not come down to dinner. I'd rather stay up in my room with my dog where we won't get harassed, and my mom feels the same way. She can't even stand to look at him anymore because of how much disrespect he has for *everybody*.

It's not so much an issue of the dinner itself -- it's just being put in the same room with everybody and having the obligation to stay there for a while. My mom and I consciously stay away from the two of them throughout the day for this reason. It breaks her heart that she has to sacrifice being around her daughter to avoid being around him.

I've spoken to my mom about me not coming down to dinner when he's here, and she gets upset. She says that "family has to stick together", meaning her and me. I would love to eat with her, but I hate being around them.

So far I've come down every time I was asked. I just hate it and I don't know what to do.
<bot>: My sister and her boyfriend are assholes to me and I can't stand coming down to dinner anymore. What should I do?