Trigger Warning - sexual assault & pregnancy

So I really need advice I’m lost on what I should do. So my SIL is pregnant we live together & are fairly close (we planned to be pregnant together lol) so our BIL (her husbands brother) raped me multiple times.. when I found out his girlfriend was pregnant I finally built the courage to say something (when I found out they were having a girl gave me the push I needed as all I could think about was that baby girl stuck with a monster as a dad) fast forward I told the family & she ended up staying with him I was super disappointed & felt like it was all for nothing.. I used to be friends with the girl but I just couldn’t stand being around her either knowing she forgave him for what he did to me (& multiple other girls including his 8 year old little cousin) i know that her husband is going to want his brother (aka my rapist) & his brothers girlfriend & baby at their baby shower & im stressing out because I really don’t want to be anywhere near him im not ready to face him & I don’t think I’ll ever be & I don’t want her to be upset at me that I don’t want to go I’m hoping she will understand but at the same time I feel guilty I don’t want to make them feel like they have to choose me or his brother idk how to even bring this up to them & like I said we live together so I can’t even just avoid them until it’s over. Idk what to do..