You might want to get some legal counsel. There is no reason for you to be the one to 'walk away' especially since you now have police and hospital records to back up the circumstances of her problem.
If she is still able to hold down her teaching job, she must have tenure and should be able to support herself. Have you ever suggested detox/rehab to her? Unless she wants a divorce perhaps she would consider this. Otherwise, I would take legal steps to protect your assets/home etc.
I'm so sorry for your situation and can identify with your pain.