unneccesarry drama

so Ive been with my boyfriend for a little over 2 years , im pregnant with our first child and we live together with his family but we have our own place in the back well , I get along with his mom his dad and his brothers the only problem is his sister -__- I dont get it , we used to get along now she wont even say hi to me or talk to me , one day I answered one of her questions but she totally pretended she didnt hear me and when my boyfriend answered it 5 seconds later she responded to him . shes always making comments that I know are directed to me , and ive been wanting to say something for the longest because its been going on for a while but I know for a fact its gonna lead to a fight so I stay quiet but today she got me so annoyed when we were all at the dinner table eating and his dad was inviting us to go to church with them and she blurted out loud " idk why they go if all they do is sit down " my boyfriend told her why cant she ever mind her own business and she thought he was joking or so she made it seem like a joke . Im done with trying to be nice to her Ive always stayed quiet about things but ever since I got pregnant ive been less tolerate with peoples bullshit and am tending to talk back to others and stand up for myself .  I dont want to cause problems but im so tired of it . it seems like my boyfriend doesnt seem to notice and it makes me feel uncomfortable even being around her . I havent done anything to her so idk why she acts like that . his mom used to make comments that hurt my feelings all the time but ever since I got pregnant she changed and is nice to me now but his sister isnt .. if you were me would you just ignore her or would you say something ?