The only thihg you can do here is give her time. Physical violence, whether accidental or not, is probably one of the hardest things for a women to forgive in a relationship. Depending on how much time has passed id start thinking about moving on.
Keep telling her you are sorry and try to make it up to her, buy her things, do what she wants you to do, be a gentlemen.
Punched her in the stomach! I thought guys did that one-on-one!!! You are a piece of work and if she's smart she'll keep going. Get your head out from under that rock of yours and realize men don't punch women anywhere! If she is getting on your nerves walk away and cool off!
"you punched her in the stomach but you didn't mean to?" Are you being honest about what happened? Take a long, hard honest look at what happened here -- punching has no place in a relationship, and you might need help to make sure it never happens again. Real men face their problems.