MIL rant: " when he's older i'll tell him to slap you in the face."

My mother in law saw my baby in his high chair in only diapers and went balistic. He was eating bananas and as anyone with a baby knows that banana leaves horrible stains on clothes. So only because of that did i leave him in only diapers. And we were home. Alone. 🙄
She basically says:"you're supposed to be taking care of our son and not leaving him like that to get sick."
He is my son before he was ever 'your son'. 😡
And she just ends it with: " when he's older i'll tell him to slap you in the face"
WTF.
I basically didnt repy to her at all. 
End rant.