I left work early to check my mail, and there it is, a letter from Tufts starting with "Congratulations..." The letter is dated Dec 17. So they must have made the decision right after the interview. I really hoped they would have called us and spare me from the grueling weekend. Overwhelmingly happy now!
The interview was, as everybody else said, very conversational and relaxed. One of the professors actually started with a joke that I may want to sit in his chair. He then told me about the structure of the interview: they will tell me about their own background, then ask me some questions, and after that I can ask them questions. They asked me about my high GRE verbal score, why do I want to give up all the stuff I did before and become a vet, and whether I know how much a vet earn in the area. After the female professor asked the "why vet" question, she immediately apologized for asking such a question! That's how nice the interviewers are! We talked a lot about the differences between USA and China in terms of animals and vet (because I am a native Chinese). They also asked me about my college, because it is a Chinese college they have no idea about. The interview feels much shorter than it lasted, which is about 45 min.
Happy happy happy!!! Best wishes to all of you!