Your son's prayer during grace says it all...you did the right thing Mom.
Now, be prepared for what will likely happen next. You will hear from your Ex. He will be remorseful, penitent. Full of "I love you" and swearing to get help/stop drinking. He will be the sweet guy you remember. THat's when you have to remember your son's prayer and stay strong. If you don't go back, the Ex may then turn on you and get ugly. That's why it's best to go No Contact and take all this game playing out of the mix. Block text messages and phone calls. Don't allow even a text to disrupt the peace in your home that your son wants.
Congrats on doing the right thing, takes a lot of courage.
