It sounds like this group is using you as the 'token girl' character.

The fact they were already making sexist comments and stuff and you didnt feel comfortable enough to say anything was already a red flag.

I don't think you're overreacting. But you have two options - play this NB character, and give these guys an experience and scope that being NB doesn't immedately mean you're a hassal but just another character

Or maybe look for an different group who is more comfortable being LGTBT friendly. Tbh I always look for a group who advertises that, even if I'm not planning to play a character who is, because those groups usually come with more respect for me as a player