He is an addict doing what addicts do.
Exposing your children to someone in active addiction is negligence. I applaud your boundaries to keep your children safe. Meth addicts often become sloppy with chemicals and spontaneously violent with no provacation.
Take time and grieve the loss of your hopeful fantasy that he was going to be the man you wanted him to be.
He is an addict doing what addicts do.
This too shall pass.