My baby girl is turning into a Diva!

There is probably a better word for how she has been acting, however I don't want to frighten any potential readers off just yet! To sum it up, for the most part she has been my good child thus far. She doesn't have the fits and tantrums that her twin brother has and when I tell her to do something she usually actually listens. Well that was until a couple of days ago...

It almost seems as if she just woke up mean one day! I am very used to her coming up to me out of the blue & giving me a big hug, saying she loves me. Now if I say something she doesn't like, I get "I hate you". She has also taken to mocking her punishments, if I tell her she needs to go to time-out for something she will say "I'm not going to time-out, you need to go to time-out".

Last week I adopted a new kitten from the shelter for the two of them since they'd been begging for a pet. She loved her so much last week, this week when I tell her that she is playing too rough with the kitten I get the response "I hate kitties" and then "You need to take the kitties all back". 

Please someone tell me this is a phase & if not, where can I buy Xanax in bulk? Ha, Ha!

P.S. I bet you all figured out the word I probably should've used in place of Diva, huh?