Don’t trust mother in law

So yesterday mi came come without calling first and ask me to leave my 6 month old at her house but I don’t trust her with him, she never washes her hands or use hand sanitizer, she tries to tell me how to raise my kid and the main reason is that when he was a newborn I ask her not to touch his umbilical cord and guess what she did? ... I catch her trying to “clean” the umbilical cord, but I thought she was trying to rip it since she did it behind my back.

Well that happened a long time ago but I still can’t trust her.

My husband feels offended that sometimes I let my son stay for a few hours with mY parents but not with his parents and I don’t know what to do.

Am I overreacting?