Why Does He Behave Like That After He Has A Girlfriend?

Hello Girl, 17 years old. I moved to a new school 3 years ago. A classmate and I got along really well. Then a friend of mine told me that the classmate in question liked me. I ignored this fact because I felt nothing for him. We gradually stopped hanging out. It so happened last year that for a few hours the ladies moved him to me. But he was acting strange. He was hugging me, holding my hand ... I was so uncomfortable, I didn't know how to react. I just laughed and backed away. And he said he liked a girl from another country. The moment came when I got tired. I scolded him. Then he started to get on my nerves. As a character, he looked good at first, but I realized what he really was. One day he got mad at me for being stupid - he hit me in the face. I felt the malice in him ... Nor did he apologize to me. For two weeks the place was swollen. This hurt me terribly. We seem to be smart enough people, but he hit me in front of the whole class! In time, this anger and shame passed. He has had a supposedly "serious" girlfriend since the beginning of this school year. But he does the same things again. He comes and caresses me, says I'm cute, hugs me, takes my hand. Today on FVS we wanted to split into teams. I got into his, but the other team wanted me. He walked behind me and patted me lightly and said "she's mine." It's not nice ... He's cheeky, I don't know how to react. I'm ashamed in front of the class. They'll think I'm dealing with him, I don't care if he has a girlfriend or not. And worse - someone to say something to his girlfriend. One day he started again with these supposed activities. A friend saw him and said, "Realize, you have a girlfriend." My classmate has a big mouth, plugged it in seconds .. That's why I can't go and tell him anything. No matter how much I pull away, he doesn't stop with this attitude. I don't feel anything for him. His impudence has no end, he has a big mouth. I don't know how to get out of this awkward situation. Help me!