So there's going to be a genderbender birthday party at my house (that i share with 4 friends). A friend who has moved away wanted to celebrate her birthday here with her friends, and we do like to not have to go anywhere for parties

Before transition that would have been great... now it's the opposite.
But let's start at the beginning.
Some time ago that friend told me her birthday would fall on ... Men's World Day? It doesn't even seem to be celebrated anymore, but whatever. And she thought it would be an awesome idea if everyone had to dress as a man. She laughed at how funny it must be for me to be a guy again for a day. I suggested the term "traumatic" instead. She was taken aback and i explained. She suggested i could just come as myself then, but i said that i don't want to stick out like that. Since the mood was getting absolutely terrible i joked that i do still use the socks from back when i was living as a guy, so maybe that would be enough to count?.
I probably shouldn't have said that.
Later she excitedly announced to my roommates what she wanted to do for her birthday party. You know, right in front of me. She added that Everyone has to look manly and have a beard. Right in front of my roommate who has expressed frustration before about how lately everyone has been talking about how manly and hot beards are and he can't grow any significant facial hair at all. He didn't seem to be bothered though, but that doesn't mean much, i didn't mention my problem with the idea either (That's because i still haven't explicitly come out to one of my roommates. I really don't feel like it).
Well eventually the party got cancelled. Okay, it got moved by a week, but i thought that since it was no longer on a special occasion and she never mentioned her idea anymore she might have dropped the theme.
This morning there was a facebook invitation. titled "hormone confused birthday party". It's a full on genderbender party now! And she encourages using stereotypes (I as a feminist am fighting really hard to get those stereotypes gone and buried. So even when it's just in a parody context i really don't like celebrating them). Better even! She added for me a line saying that whoever already had a sex change doesn't need to change anymore. Sure that could be seen as a joke, but there actually are rumors about me (thanks to friends not having been as careful as they should have been). So if i go and don't change it will probably be mentioned (even if as a joke) and if i ask to remove that line, it may look suspicious to whoever has read the text already. Usually i rely on people being oblivious about anything out of what is their norm, but i'm not sure i can actually risk that now. I hoped she had only invited people who know anyway (that's actually not a small group of people!), but no, there are several people including some who i have been purposefully making sure they don't find out (no special reason, i just don't think everyone has to know).
So, right now i'm not sure what to do.
possible solutions:
I participate - NONONONONO
I'm there but don't crossdress - That one line in the invitation basically kills this idea. I might be lucky and some won't crossdress, but that's unlikely (except for the guys. And i imagine some friends might not do it to support me). Still this whole party is pretty uncomfortable for me.
I stay in my room - That'd be noticeable. also it sucks to hear a party in your house and to be stuck in your room.
Stay at someone elses place for the weekend - Everyone is invited, so that makes this one a bit difficult, but i'll check. I'd have to take all my dilation stuff with me of course
I ask her to drop the theme - A bit of an egoistic move. I mean, sure i have objections, but the worst part is really just that i don't want to be outed nor feed the rumors and that it is going to be uncomfortable for me. Genderbender parties are after all beneficial to pre-transition transsexuals as well as most on the transgender spectrum. (then again it does kinda enforce the binary? argh it's all so problematic)
This is an absolutely terrible start to the day and is probably going to make it hard to relax when dilating. yaaaaay ...