I (27/f) want to skip my brother's (30/m) wedding to go to my friend's (30/f) wedding

I'm sorry if this is long but the background is important I think: I am 3 years younger than my brother, Jim and we are the only 2 children in our immediate family. My entire life Jim has not liked me. I guess I always thought we would grow closer as we got older but that doesn't seem like it's going to happen. Literally, one of my first memories is Jim yelling that he didn't want to play with me because he wanted a brother and not a stupid sister. Okay- just kid's stuff. My parents chose the neighborhood we grew up in because there were a lot of kids and we were basically turned loose in the morning and could come back at night. Jim went out of his way to get me actively excluded from this group of kids. And not in an annoying, younger sister wants to tag along kind of way- he went to all the girls my age and told them things like I picked my nose and ate it and that I never showered and I was gross and told all the boys my age that if they played with me they would never be allowed to play with him and his friends. Because out town was small, these were also all the kids I went to school with so I was pretty alone at school to. The only person who was ever kind to me was Ashley. She had 3 older brothers that were total All-American, perfect athletes that were all older than Jim so she was untouchable in our neighborhood and could do whatever she wanted without getting messed with. When Jim tried to tell her I was gross and stupid she said I wasn't and would hang out with me. Pretty much, Ashley took me under her wing, hung out with me and, as we got older, would eat lunch with me in school, walk home with me, etc. When she graduated before me, we stayed close and have been best friends for most of our lives. We live in different cities across the country from each other and have since she left for college but we facetime literally 3 or 4 times a week, visit each other a couple times a year, we made it to each other's college graduations and I was the first person she told about her engagement after her family. By contrast, my brother left our town for a college 30 minutes away and literally the only texts I ever got from him were "mom says i should tell you happy birthday" (actually that was on my facebook wall) and "don't tell me you're thinking about coming here" when I asked him about scheduling a college tour of his school because it had a good program I was interested in.
Jim met his fiance Laura in medical school that's about a 7 hour drive from me right now. and they are in their last year and waiting to hear about residencies right now. They have been together for 2 years and I have met Laura maybe 3 times. She's always seemed nice, she's very sweet to my parents and she and Jim seem happy the few times I've seen them together but I don't know her well at all. I only have her phone number because my mom gave it to me. They are getting married in June and they hope to be matched in the city where they live now (you don't really get a choice with your residency-they tell you where to go) because Laura's from there and Jim and I have a whole bunch of cousins in that city. They are getting married in June in that city as well.
I work in a field where, ultimately, you need a PhD to advance. I started looking at programs and one of the best ones in the country was in the city where Jim and Laura live, but at a different university. When I applied to that program, my dad told Jim that I might be moving there and Jim said "yeah but she's going to have to get in first so I'm not worried". I did get into the program and moved to Jim's city over this past summer to start my program. I couldn't even get Jim to answer an email about good neighborhood's to look at and that's when my mom gave me Laura's number to text her with those questions. Ashley's response was for her and her fiance to take a week off work and help me move. Since moving to this city, I have seen Jim 3 times and one of those times was at the airport after my mom said she wouldn't help Jim with a plane ticket home for the holidays unless he coordinated his flight with mine. I know he's busy but I literally have a text history of monthly asking him to go to dinner or lunch or for a run and him either outright ignoring me or saying no
Ashley is having a very small, family only destination wedding in the country where her parents are from originally the same weekend as my brother, I'm the only person she's invited that's not related to her by blood or marriage. She told me that she totally understands that I will have to miss it for Jim's wedding. I was sad too but felt like my brother came first
Last night I went out to dinner with my cousin. He's pretty close to Jim but he and I have always gotten along well and there's enough of an age gap that he's more like an uncle. He said he thought Jim was being ****ty about the wedding and that he'd called him on it but that I should know some things. My cousin told me that:

• Laura had asked Jim if she should ask me to be a bridesmaid. Jim's response was "why? she can't handle that. she probably won't even make it to the wedding with her bull**** excuses" (the only big life event of Jim's I've ever missed was his high school graduation and I was in the hospital with a burst ovarian cyst) -Laura asked if they should have me do a reading Jim's response was "that should be from someone that actually gives a **** about us". I don't even know where this is coming from/ -Jim said that if I wasn't his sister I wouldn't be invited because he doesn't associate with people like me. My cousin asked him what he meant and Jim couldn't clarify just that "you know how she is"
• Apparently, Jim has said to multiple cousins on multiple occasions that my mother should have given my father a ******* the night I was concieved
• Jim is dreading me coming to the wedding because "it's another event that's gonna be all about her" when my cousin asked what Jim meant he couldn't provide any answers of events that I had ruined.

I am heartbroken and I am ******. I want to tell Jim to go **** himself and skip his wedding. I want to go and show my best friend who has loved me unconditionally that I love and support her on her wedding day. My concerns about doing that are that I think I could still have a relationship with Laura somewhere down the line as she tried to include me in the wedding and I'm worried that skipping it will cut that tie forever. That would probably also mean never having a relationship with any kids they may have down the line. Also, I don't know how to have a conversation about this with my parents. They's always believed that Jim and I would get closer as we got older and when they see us together Jim and I are cordial to each other. I can't fathom how I tell my parents all of the things that Jim has said. How can I ask my parents to pick between their only 2 kids. Whose wedding do I go to? Do I suck it up and go to Jim's even though he hates me?
TL;DR: My best friend and brother are getting married that same weekend. After finding out some of the things he's said about me, I think I want to go to my friend's wedding instead but I'mn worried about what that will do to my relationship with my family.


Source.

Go to your friend's wedding.

This is one of those times where hearing the brother's side of the story would be interesting, I bet.
And the "you shoulda been a blow job" line is classic

I would bet money you are being over dramatic.