HI Peapods,
I totally agree with everyone else. You need to educate yourself on addiction and co-dependency. Part of the symptoms of this man's addiction is his affair with you. Cokeheads are notorious for cheating and having a sex cross-addiction. His cheating on his wife with you is just indicative of the type of life that awaits of ryou if you stay involved with him.
Also, sounds like you could really really use some therapy for your own life/relationship as well. Women rarely cheat merely for sex alone (as oftentimes men do), women usually cheat because their emotional needs are not being met, or other similar reasons.
Good Luck and I hope you get this sorted out.