I have a 5 year old daughter and in the last couple weeks her behavior has completely changed. She's starting to be super disrespectful towards me, telling me no, running and hiding when I say it's time to do something. Now she has started to hit and scratch me out of anger or when I ask her to stop doing something to my body she laughs and keeps doing it. She has always been violent towards our cat since we got him (about a year ago) but it's gotten worse. Now she has started choking the cat and laughing while doing it.. The only two things I can think of is

1. My little brother died last year (but why would her behavior all the sudden change after a year?)

2. I'm 28 weeks pregnant and maybe she is getting jealous even though she says she's excited for her baby brother to come..

I'm starting to get really worried because it's getting out of hand and I don't know if this is normal behavior. I want to cry because this isn't how she usually acts and I'm having a hard time wanting to be around her.. I honestly just want to leave for a few days or a week. I don't know what to do or how to help, please give me some advice.