I agree, don't tip your hand to your ex yet. Speak to your attorney and find out what recourse you have, what evidence you might need, what steps you can take, etc.
Also - I don't know if there are people in his life (NOT you) who might be able to do an intervention and get him into treatment for his alcoholism? Does he have family or friends who can see it? Because the best result for everybody would be for him to get treatment and get sober. The second best solution is for him to have supervised visitation.
