you didn't come here for advice. you came here for people to tell you what she's doing is perfectly normal so that you'd feel less weird about it. but the mere fact you came to ask about it lets you know that you're not ok with it. first decide if you're even genuinely asking for help, before you complain about not getting it.

substitute her fetish with something else equally as strange and see how you'd feel about it: "my gf is into hitler and wants me to dress up as hitler when we have sex" "well hold on lets hear her out, does she want you to be hitler 24/7 or just in the bedroom". get the fuck out of here with that shit. if you think im some kid who is a virgin, what do you think the people telling you it's perfectly normal and acceptable are? think those aren't kids?

there is nothing anyone here can tell you that you don't already know in the back of your mind. you asking about it is simply the process of going from denial to acceptance, this post asking for advice is the bargaining phase.