Is locking your kid outside for 2 hours considered child abuse?

Last night my mom and I got into a fight and she threw me outside and she shut the door so fast that she caught my ankle in it. My mom came outside and videotaped me, called me a *****, and told me the only thing I'm good at doing is eating (I'm about 30-40 lbs overweight). I sat on my porch for 2 hours with no jacket or shoes (it was really chilly and windy here yesterday) until my Nana got home and I walked to her house. I ended up having to spend the night there. She also wouldn't let me come in the house to eat or shower. Is this considered child abuse? Is there anything I can do to get out of this situation? My mom also said not to come home after school so I don't know if I should just go to my nana's house again or go to a friend's house. Help me? My mom is also abusive (verbally and physically).