When your So gets a pet out of nowhere

Crickett★★★
I live with my boyfriend. We have fairly busy lives, a toddler, and a 7mo old puppy, and he's military. Today his phone rang and apparently he is getting a kitten. I love animals but I am not excited. I lived with my best friend as room mates and she is borderline an animal hoarder. He cats were disgusting. I think that's why I am dreading him bringing home a cat. Plus I wouldn't trust my dog with a kitten as she has a high prey drive. I know he's been wanting a pet since before we got together. He was looking at dogs for awhile. Should I support him? Why am I prejudged against this kitten? All I can think about is a gross litter box. Plus we are TTC.