What do I do?
I have a stepdaughter (6yo) and a bio son (7mo). My stepdaughter requires constant "reminding" from her mom... 5-10 times to do a task. Mom (my wife) has rare consequences for misbehavior and just explains why she shouldn't or should do something. Things changed this weekend when 6yo held the 7mo by his ankles upside down. When mom freaked and told her to put him down gently she put him down on his head and let go. The baby's neck bent and he flopped flat on his back. My wife said he was laughing the whole time but she (my wife) was panicked that he could've broken his neck. I've told the 6yo explicitly NOT to do this about a week before this happened and just because mom and I do it doesn't mean she can.
My wife told me about this event and said she "took care of it" with the 6yo. I pushed hard that this is unacceptable behavior and she needs consequences to disobedient behavior. To make a long story short we had a sit down with the 6yo and explained that she needs to listen. Later I had a sit down with mom and explain how angry and scared this made me and the 6yo needs to start listening, that this disobedience endangers the life of our son and I may leave her if she something doesn't change.
This is not the first time this has happened with the 6yo. She goes off and picks up the baby without permission. She's fallen off the bed while holding the baby. She's very clumsy and in 'trying to help' disobeys us and does what she feels is best.
My wife said she would crack down on the 6yo on Say night but nothing changed on Sunday when it came time to be firmer. Nothing ever does change. My wife is always all talk and doesn't see her daughter as disobedient, only 'trying to help' and she doesn't want to squash her spirit.
I'm really scared, angry and not sure what to do. Can someone please offer advice?