no offense to you mother in law, but it sounds like she needs to but out of your life and let you raise your child how you want to.. plus your son is only 13 months old. he's supposed to eat with his hands and touch everything that's how kids learn. just let her know that she raised your husband and HE and YOU are raising YOUR son. and as for the hitting you, does your husband know? and if he does why has't he said anything to her? I would tell her if she can't respect you and your life then she has no place in it. sorry it may seem a little harsh, but i dont like the idea of people hurting other people just cause they can. hope this helps!
FIRST, how dare she raise her hand against you? SECOND, i can't believe you even allow such a person to continue to be apart of your life, especially your child. if she can strike you, what makes you think your child is safe in her care/presence? you CANNOT please this woman, no matter how much you change your habits raising your child. my advice? kick this woman out of your life and your childs' until she can control herself.
Are you and your husband living with her? If so, move out. It's better to share a studio apartment than to live like that. Is your husband on the same page as you? Being away from her is better than being near her, even if she is supposedly helping you out. She's bad news.