It is never justified to hit a woman or man for that matter. Not only is is not right to do it out of joulousy, but it is not right under any circumstances... even if his doubts are real, even if you are cheating on him, or even if he catches you in bed with another man.. it is not correct.
Contact me and we shall discuss this further. It my previous relationship, my wife used to beat me out of jelousy.