I'm going to tell my boyfriend he can't adopt a cat that looks identical to mine that died 3 weeks ago
Why should you tell your boyfriend that? Are you sad about the loss of your cat?
Somebody already told me that my boyfriend is totally into cats and then I found out that he was actually planning to adopt one.
I'm sorry for your loss, but eventually you need to get over it and have a new cat. You boyfriend should be allowed to have a cat, as it will be his joy and eventually yours too. Lots of cats need adoption and they might be euthanized if you don't help.
It's okay, I'm going to tell him that I don't even like cats anyway.
It is nice to have pets and you should respect someone's desire to adopt an animal.