Hi and welcome cjgodfryt
I'm sorry for what brings you here - sounds like a very tough situation.
The welfare of your child, as well of that of you and your wife, need to come first here. If your mom can't or won't stop drinking, I think you're entitled to lay down whatever boundaries you see fit to protect your family.
Needless to say this won't be easy or pleasant, but you're not alone here.
We also have Family and Friends forums you may wish to check out as well
D