please read. idk what to do.

no one in my family is any help to me, i really just need honest opinions. i’m from a different state, but my mom and i moved here when i was a little kid. so the only family i have here is my step dads side. i’m 16 weeks pregnant. my step brothers fiancé is also pregnant. they both have caused me so much stress even way before either of us got pregnant. my step brothers fiancé used to be a close friend, but ever since she got together with my brother, she’s betrayed me in a lot of ways. things I won’t get into, but it really hurt me and impacted the way I look at her. the entire family coddles my step brother. ever since we moved here, i’ve had to take a backseat to him. he is the family favorite and I have always been shown that I am not as important because i’m not a blood relative. my parents tell me I have to be fake to both my brother and his fiancé, because they don’t want to hurt his feelings. when my brother is told something he doesn’t want to hear, he goes OFF and will stop talking to you for months. he’ll also keep his oldest son away from us just to teach us a lesson. i’m so tired of being fake to save his feelings. his fiancé has made our pregnancies a competition to her, she throws it in my face that she has more than me and how my family loves her so much, trying to make me feel replaced (i just nevermind that drama) but my question is, I don’t want her or my brother involved in my big life changes. I don’t want them at my gender reveal next week, I don’t want them at my baby shower, and I don’t want them at my wedding sometime in the next year or two. but if I voice that to my mom or step dad, they would go off on me. blame me for the way my step brother acts, and make it known during my events that they would be happier if he was there. I have an anxiety disorder and am currently battling depression. I can’t handle this on top of my daily stress with other things. do I go against what my parents have been forcing me to do for years and do what I want? or do I continue to be fake just to keep the peace and continue to be miserable? anything helps. i’m so beat at this point