NM -
First - I didn't realize that Crohn's disease was being considered as a diagnosis. If he has chronic abdominal pain, he should definitely be tried on a gluten-free diet:
http://www.celiac.com/st_prod.html?p_prodid=1170&p_catid=82&sid=91hH9H1jk2dc3GX-13107278578.95

Of course, right now he may have abdominal pains any time he withdraws from the pain pills, since narcotics addicts have a lot of cramping and pain when they go through withdrawal.

I don't blame you for being fed up. If you can do anything to get him clean, though - even if you plan to leave - it will be better for your kids to have a sober dad.

Ellie