Ive been holding this one in for a year or so now, its a long one(sorry) but.. here we go. Would I (25F) be the AH if I don't attend my Dad's(45M) wedding with his soon-to-be wife(60F) by faking the flu?

So, long story short, my dad is getting married soon. Like, they're getting the license this weekend i believe and having the wedding this month or next at the latest type of soon. And my dads wife (I refuse to call her stepmother, just her name is fine) is demanding I attend, regardless of whether or not I have work or who knows what because "the wedding is more important." If I do not attend, unless I'm severely sick or dying, I am basically going to be shunned entirely from the 'family' and on the streets. Unfortunately, I'm living with my father right now due to some not so good circumstances.

Anyways. Lil bit of backstory. Dads new wife, we'll call her Bethany, has made it clear she hates me and is now putting on a facade for my dad. I can tell because she's been somewhat nice to me since getting the news of this all. Last year, in the summer, I tried staying here because of where I had lived at previously. Bethany screamed at me every day, fought with him every day screaming, "you're really gonna take that bitch's side?" And so on so forth about how she can't stand me and how disrespectful i am(I would ask her to not yell at me or cuss at me, explain my dad and I were talking about music etc not talking shit bc we're accused constantly of it) when he tried to explain what was actually going on but that made it worse somehow. I mainly kept to myself in this room because she, quite literally, had her nose up in the air anytime I was around and barely acknowledged me unless she needed something or would scream at me(everything is a personal attack to her, i truly dont know what ive done.). I have been called numerous names before by her, including a C U Next Tuesday and was told over and over to get out by her(my dad begged me to stay.). So I left last year after i had to push her away from me because she got in my face like she was going to hit me and smiled about it while flipping me off. I moved place to place for a bit sadly and now I'm back because it's currently my last option and no, i didnt ask to come here but rather Bethany had offered because i was getting pneumonia back to back where i was at previously. They still fight and scream all the time, mainly about me and her kids. He'll bring up an issue, somehow her kids are brought up by her and then she'll throw my name in the mix to egg it on and it's hellfire from there because my dad gets pissed im brought up. Anytime I try to talk about myself or anything, really, she completely dismisses it and brings up her kids and what they've done and what she's done and how she feels, etc. Any accomplishments ive made? "Oh so and so did that" and "oh so and so did better" and things like that. I have tried to build a relationship with Bethany, even spending time but she never wants to do anything i suggest unless it's what Bethany wants. Ive done everything i can and she does not want me around except for her, her kids and my dad minus me. I know my own mother didnt want me, and chose drugs and other bs over me, but i dont deserve this. Its hard enough to accept my own mom not wanting me and not being around, but the woman marrying my dad claims she loves me and wants to be like a mom to me is treating me like this/that? No. Even my own mother wouldnt do that, i would know because shes finally been reaching out the last few years since being locked up. Ive been sober, never addicted to anything(i had my fun at 18-20yo like every normal kid) unlike her kids as spiteful as that sounds. Ive never been addicted to meth, heroin, coke, none of that. Most ive got is almost 3 years free of self harm, which Bethany has used against me multiple times, "my kids aint suicidal like that!"(my scars are noticeably all over my arms and thighs) and has threatened the police on me, saying she'd lie to them about me as well just so id go to either the hospital or jail, which i dont have a record either btw. Not once have i caused problems or tried to split them up. I dont care whether or not theyre together because it isnt my relationship or my place to say anything, i dont really have that right imo. However, i dont have to be loud about supporting them because I'd be lying to myself if i did so i pretty much just smile and wave lol Ive stuck around, too, as much as i can. I've been nothing but nice and kind. Bethany's kids did not and did everything possible to split them up, including not talking to them for years at a time and making up lies about each other to stir up bs. Including accusing me of taking a blanket when i was over 2,000 miles away in New York and the blanket was here in the house(we live in Kansas.). My father and her have been together for almost 7 years now. I am not allowed to have a relationship with my dad anymore because of her i have learned. Even being on the phone with him, I was always on speaker because of her i had zero privacy to talk with my dad about anything and i still dont. He cant even leave the house without her but she can without him, and Bethany will call him back to back while shes out. She smothers tf outta him imo, constantly all over him(normal ig for some) but based on his body language and tension, hes uncomfortable and unhappy. If I'm in the same room as him without her, she loses her mind and becomes incredibly insecure sadly. She is always around. I dont even have phone calls with my friends because of her, shes always eavesdropping. It's just so fucking much, I could go on and on and on but this post would take hours to scroll.

I do want to mention as well, I don't know if it's relevant, but Bethany treats my father worse. She has admitted to hitting him and laughing about it. He has told me that she's thrown things, including parts of his collection and whatnot. And so much more, too, ive seen it and i have recorded things just in case for my safety. It breaks me everyday he's here and I wish I could just take him away from it all because all I've ever done is see him struggle my whole life and this is the worst I've seen my dad go through. I want to be there for my dad, but I'm at a loss on what to do. I'm the only one who's there for him, his family isn't around either so they're kind of useless here. I can't really talk to him anymore either, he's always angry or anxious or sad because of her. I had never seen my dad cry until I came here. I'm sorry this is SO much but I wanted to add as much info as possible.

Anyways... so, reddit, would I be the AH if I did not attend this wedding by faking sick? Even if it puts my life at risk lmao? Or how should I go about this instead? I understand a part of me is being prideful, too, and I should just suck it up and go but jfc I would rather chew on a wet jean jacket because of what I have had to endure.

TL;DR dad's abusive new wife requires I attend the wedding or I cease to exist in the family and lose everything. Should I still attend?

ETA: I'm so sorry this is all over the place or if it's complicated/confusing and I will add an update if needed, too.