Consequences on Stress on Children's Development

I remember spending the night at my them BFF's house for the first time ever. We stayed up late, played on the phone did each other's hair and talked about what career's we wanted. That Saturday morning her mom woke up up very early as our punishment for laughing and playing all night. I remember thinking, my mom would have never done this to us.We did all that we were told to do sweep, wash dishes, mop the floor, clean the bathroom and dust the living room. We were tired and worn out. My friend called her grandmother to complain about what her mom made us do, her grandmother requested to talk to her mom and that was the beginning of the sleep over form hell. Once her mom ended the conversation, she stormed into the room, where we both were watching television, with a belt. Her face was red, her eyes were huge and her lips were tight. At that moment she just began attacking her daughter, repeatedly hitting her with the belt. She was screaming and had balled up into a fetal position. I was frozen, stuck and confused by what was going on . I wasn't being hit but, I flinched with every hit her mom landed on her body. I was so afraid that she was coming for me next. After, the beating was over, her mom separated us and began yelling about how she was a good mother, how she gave up so much for her and how could she call to say she didn't want to be there anymore. Obviously  the phone conversation made her irate. I wanted to cry but didn't .I wanted my mother so bad to come and rescue me. 

As soon as my mom entered she sense something was wrong. My friends mother began to explain what happened and her actions. My mother entered my friends bedroom and saw her still balled up on the floor. She was sore to the touch, black and blue and blood soaked into her clothes. My mom exit the room with disgust. She asked if I was hit and immediately asked my friends mom to talk in the other room. Soon after we left. I never spent the night again. I was too afraid. 

In school her grades were never steady, she was always in danger of failing. She didn't have many friends, her attendance was poor and she was aggressive towards all adults and authority figures. We are no longer friends but, I would like to know how she is functioning as an adult.