Pinched 1 year old. All his milestones!

Hi my baby boy is 16 months old.due to frustration and anger I used to pinch him daily since 11 months and I regret it always I have bipolar disorder iam on medications there is no 1 to look after my baby I really do care him a lot I regret later for taking frustration on him .now due to pinching the skin became black and red will this reduce he doesn't have pain now will this cause any serious issue iam trying to be far from my kid when ever iam getting frustrated .my habana stays in other country iam at my in laws home they always make taunts that frustration is going on baby when he is being stubborn plz help me will it get cure will it cause any serious issue.he is very active and reaching all his milestones