I don't think I can take this to my other roommate. For one, she and the first roommate are friends and don't have trouble with each other. Also, I don't feel it's fair to try and bring her into this.

I'm nervous about talking to my roommate in person because I think that after I make my complaint, she's going to shoot back and I'm just going to fold up and slink away - I have a hard time holding my ground in these situations. If you want me to talk to her in person, what should I say? Start with the cat conversation this morning and basically say "I've been thinking about what you said, I don't think it's appropriate, I don't think it's a problem if the vet I took her to didn't say it was and this is typical of your behavior towards me and I don't like it?"

EDIT: If I don't bring this up in e-mail, should I at least send her an e-mail saying I want to talk to her?