Sad to say that now is the time for you to retain the services of a lawyer. Her stay in rehab gives you some time to think and to act. Yes, it may feel "sneaky", but as you have pointed out in your latest post, she could very well get sober and turn the tables on you. Mind you, that sobriety would be short-lived if it was solely motivated by anger and revenge, which in the end would be detrimental to your children.
Again, this isn't something you can control. So focus on what you can control: yourself.
Act now. (sorry if this sounds like an informercial).