Is my girlfriend over-reacting?

I am addicted to cocaine and one night when I was watching her child while she was at work I did some coke in front of her child and the child got into it while I was in the bathroom. The kid ended up being ok but my girlfriend started to yell at me which made me lose my temper and I hit her. She hasnt talked to me since and everytiime I call her house her dad tells me that she is filing charges against me. I dont know what to do and I want her back...