not sure if this is abuse or if I'm crazy

So I've been in a long term relationship we got engaged in August. He's put his hands on me 3 times so far never hit me but has pushed me or grabbed my face before. A week ago I was taking my birth control and he chased me down the stairs to stop me from taking my birth control, because he wants a baby but I'm not ready. Then we were driving in the car at midnight going home with me 3 year old in the back seat and he was driving on the shoulder of the road not paying attention it was -15 out he stopped the car on the express way and got out in front of my son. I've been in happy for a while I need to get out but I don't know how, but I know it's time. Please help because I know I'm not perfect in a relate but I know the behavior I show is not normal or healthy.