So before I get to the actual scenario and question, I feel like some other information needs to be laid out.

My brother recently got engaged. He nor his gf have said anything to me about it at all, but evidently his now fiance mentioned wanting me to be part of the bridal shower. I was pretty upset by this, and will explain why shortly. I still have never had any kind of conversation with my brother, or his gf, but have reluctantly agreed to be a bridesmaid IF asked.

As far as the gf goes, I'm not a fan. She treats my bro like garbage (insults him and just generally doesn't treat him with respect), makes fun of me and my friends (in a malicious way), is extremely childish, causes drama every time she is near us, and is very manipulative. My brother isn't always the nicest person, but he bends over backwards for her. I'm trying to be as pc, and objective in my explanation here, so bear with me. Also to be clear my brother and I are not exactly close. I am appalled that my brother would be with someone that treats him the way she does, but that's his mistake to make.

I am a very shy, anxious person that doesn't like a lot of people, attention, or even things like photos. I work every day except Thursdays at least 8 hours a day depending on the demands of my work. My "free" day is spent catching up on chores, and other things that I can't get to when I'm working, as well as catching up on sleep. I've made several attempts to befriend bro's gf only to be ignored, or infuriated by the actions of gf.

So, fast forward a week or two from when I heard the engagement news secondhand from my parents. I had already stated that I would reluctantly be a bridesmaid, but nothing more. No planning, no decorating or anything like that. Gf and others plan a meeting with both sets of parents, myself, and the gfs sister. I never responded to the flood of messages making these plans that came while I was working. My parents wake me up on my day off to inform me that it's an hour before time to leave for the meeting to which I reply that I was not going. My parents blew up at me calling me names, and telling me how ridiculous I am by not going. They also kept saying he is my only brother, and it would be awful for me to not be a part of his wedding. I simply waited for them to be done, and went back to bed.

I agreed to be a bridesmaid, but made it clear that even that was not something I wanted to do. I'm really only doing it because my parents know how to guilt trip me, and despite not being close, I love my brother.

Is it terrible of me to not be part of the wedding planning? Is it expected of a bridesmaid to do that? I am really unsure of what to do because I don't have any experience in this area, but I'm very against having anything to do with the actual wedding while I want to be supportive to my brother even though he probably could not care less.

Any advice, thoughts or opinions would be excellent! Please be honest and blunt because I really need help to figure out what to do.