My friend is having a boy/girl party and i don't know what to do?!?!?

ok so i have two best friends from elementary and one of them is having a boy/girl party. shes inviting whole bunch of girls i don't know!! i've kinda met them before and some of them are annoying and strange plus, they don't talk to me whenever im around my friend they act like im not there! My friend that's having the party,really change since she met these girls and i don't want to end up like my friend, and then shes inviting her crush! what im scared of is, that her crush has done some bad stuff in the past during birthday party's! and the girls she is inviting has witnessed my friends crush doing bad stuff. Shes also inviting my other best friends crush and when my other best friend is around boys she acts like she so cool and gets really bossy and makes me cry (sometimes)! I feel like im going to be left out just because the only people there that i'll know is my two best friends! and their probably going to be trying to flirt!!!! im not into boys yet and i get left out a lot when i go to boy/girl parties!! so what should i do if im left out again or my friend starts being mean to me? any ideas???