I am dating this guy but he grabbed my arm and it hurt and now I am scared of him, what should I do?

Love to play wizard101 and pirate101 I love party's and I am the life of the party if you have a party you know you can invite me but be awear I will trash the house I love ice cream and cake breakfast real names star and I am 16 year old girl and I try to help you so is confused ask me I'll try to help you have faith.