Am I in the wrong?

Em

My sister asked me to babysit her two kids, one is 1 and the other is 3. I said no. Because when I was with them the other day, my 3 year old nephew had angry hissy fits the whole time. He was throwing things, crying and screaming, hitting people, he then kept kicking me and charged at me to hit me. If I hadn't of caught him he would have slammed into my stomach. I am 8 weeks pregnant. I have had 2 consecutive loses, my daughter was stillborn at 26 weeks and I had a miscarriage at 6 weeks. So I am overly anxious about losing another baby. Also, I have been very nauseated and generally feeling crap. She didn't apologise for his behaviour and at the time just sat there. She is now not talking to me.