WDID when my older sister's relationship is exposed because of me and now the family is breaking?

Buckle up; this is a long ride, but please stay because I really need help. My sister (22f) has been dating (29m) for about a year or so in secret from our parents. I (18f) have been dating (17m) for two years in secret from our parents too. Both of our relationships are secret because the guys are non-members of our church, but the difference is that my boyfriend is more welcomed in the family because he is an active non-member who has more of a close relationship with my family. I feel the need to add that although he isn't liked by the family, he wasn't disliked either. He is genuinely a good guy who has bought food for our family and is always there to help. I would genuinely like him if I didn't know that he assaulted my sister at the beginning of their relationship, not with ill will but because he was also assaulted multiple times as a young boy. Our relationships and how we handle them are extremely different; my sister and her boyfriend don't leave each other's side, which irritates me and wore down my relationship with her. When it was girl's Day and she went out with her, she would call her boyfriend to join us without asking me if it was ok first. She does this because supposedly he has anxiety and paranoia about what could happen to her, but I think that's a lame excuse to just be together because he doesn't act like a bodyguard; instead, he just talks to her, and I feel like a third wheel when it was originally a girl's date. A few days ago, there was a religious assembly, which she invited him. She didn't stop texting him a single minute, even though he was driving, and then took pictures of where she was sitting so he could be close to the family. I told her to pay attention and to stop holding his hand like a toddler for everything he does, I was ignored. During lunch, we have a tradition of almost 10 years of walking around the building (it was orginally to find a "assembly crush") but for the past 2 assemblies she calls him to join us. I asked her why she was doing that and she responded with straight up nonesene saying "well, he's handsome and cute and he's so cute". I was very irriated that it was the second time and decided to not third wheel and left them alone. Then I went with my parents and near the ending of lunch my sister and her boyfriend came together while my mom was talking to a person of position inside the religion, he asked who the young man was and my mom said that it was just a study. Context on why leaving them alone was iffy: There was a rumor going around that church that one of us had a boyfriend that was a non-believer. This happened because there was a guy, let's call him X, that was obsessed with my sister. X was very jealous of my sister's boyfriend (he just thought he was a study). My sister was tired of X and confessed that she was dating the study. X basically acted like a middle schooler and told everyone that she had a boyfriend. So leaving them alone was basically confirming to the church that she was the one dating and not me. The next day after the assembly, I was reflecting, and I was sick of my sister's behavior and told my mom that my sister was texting him and that she went to look for him during lunch and that I hate how he's in family pictures and how my friend told me about the rumor, etc. She agreed and said that she will talk to my sister after she comes from work. My mom doesn't know that my sister was never at work and called in sick to spend all day with her boyfriend. My mom and sister had a talk after dinner, but my mom switched up everything, saying that a person of authority inside the church told her about the rumor and how she saw her looking for him during lunch. My sister snitched on herself. My sister is now in the middle of public humiliation and pressure from my mom to move out. My mom has been insulting her for things that aren't even relevant. My mom is also resurfacing her bad anxiety attacks, faulting my sister. Since then my sister cries every night, and it's also affecting my other sister (12). My sister also confessed to me that she feels like another part of her takes over when she is with him, a part that doesn't allow her to think rationally and ignores everything. I told her that I understand that she feels like the whole family is against her, but I will never leave her side. Today is the deadline for my sister to make a decision: marrying him or breaking up with him. The decision is harder than my mom thinks; my sister has always been weak-willed, and she got assaulted by him, so their bond is kind of messed up. I tired reasoning with mom but she straight up told me that she is in denial, I even tried to put the "what would Jesus do?" but she just told me no, that is is angry and hurt and their is no reasoning with her. She has also taken away the permission to use the car to my sister and me and my little sister are heavily discourage to communicate with "bad influence". WDID, I feel like I pushed the trolley cart and the victims don't know I pushed it. I'm also scared that my secret will come out if I confess to my sister that I pushed the trolley cart. (This is my first post; sorry for the long post.) Please ask any questions; I'm happy to elaborate.