I slapped my girlfriend, is it wrong?

She told to me to eff of,, I slapped her, I think it left her with a black eye.. now I feel guilty,, (this is the first time,) so should I dump her now and move on cause she is the main culprit here inducing me to act so violently.. or should I slap her again,, and tell her to eff of,, instead of saying sorry like the first time..