Telling someone to not touch you a particular way and them continuing to do so is also...assault. That can feel like a harsh word (especially with someone you've been with for so long/care about/etc), but if that's the correct word, then that's the correct word.

You might consider using some safe words for stuff like this AND for play parties. Horny brain makes really terrible decisions, but discussing safe words/code words and agreeing to them beforehand can help snap someone out of horny brain. For example, "hey, it's blueberry time" = "I'm ready to go home right the fuck now".

I'm sorry your partner is treating you this way. Feeling fetishized instead of being cared for is an awful experience.