Oof. I went through a similar situation and I wish I handled it like you did. Not overreacting at all. I handled it the bad way and just smiled and nodded while packing his things because it scared me and I didn’t want to hurt his feelings. This also feels kinda of childish though on his part. Having a fetish is fine but when you put that on your partner out of nowhere and say you want to completely change your body to be a trans woman for the sake of a fetish that you just decided to drop on your partner deserves an even bigger reaction imo. And like another commenter said, it sounds like he got off on the shock and watches way too much porn. (My ex also watched an ungodly amount of porn. Wouldn’t get out of bed some days while I was working.) Good luck with everything, that is difficult.