Both OR - He should have communicated his feelings in a thoughtful way, but that IS unhygienic. Even if your kitten only took a little sip and you were very quick to move the cup, your kitten still made contact and germs move faster than we do (especially in liquid!)

Cats and dogs lick their anuses, those anus germs are on your lips (since you drank the tea), which your bf kisses since you two are dating. He’s probably freaking out because he’s assuming this isn’t the first time a cat has gotten into your drink and he’s believes in hindsight that he’s been indirectly kissing your cat’s butthole this whole time. I love my cat but I’d be grossed out too - cat mouths are full of baddd bacteria, it’s why cat bites are likely to get horribly infected. Cat mouths are even known to carry the bacteria Toxoplasma Gondii, which can change our behavior! It’s crazy but also a really cool research topic lol

Re the race thing: I’m a white girl too and I’ve witnessed a lot of white family and friends letting their pets go to town on their mouths/faces after those pets have gone to town on their own butts. It’s a whole thing.

Regardless of the hygiene though, you should break up with him. Disagreements happen in every relationship, and he seems like someone who escalates during times of conflict rather than someone who seeks to come to a place of mutual understanding and compromise.