MTB once he used you up he had to find another source to supply him. Alcoholics are like that. Once he uses up the person he's with now he will start going back through the ex's.....or the past sources of supply he's used before.
The true nature of alcoholic/addict is to do whatever it takes to meet their needs. You are simply a tool to them. You are not a person, but a resource to use up. There are tons of stories in these forums about being married to an alcoholic/addict, he/she cheats, leaves you for another............only to later call wanting you back. Its even happened to me!!
But when he calls try not to romanticize it. Don't romanticize anything the alcoholic/addict does because it is ALL done in an effort to fill their weak & ravenous souls. Try not to be too excited when he calls. Try not to get sucked in to relieve your own pain. If you feel physically or sexually attracted to him (come on, we've all been there) try to get over those feelings.
I send you lots of love. I have been there. Many of us have. The only meeting/phone call you should be interested in is his 12 step recovery ammends IF he gets in recovery.....and that may take a while. If someone can walk away from you......let them walk. Your destiny is never tied to anyone who didn't stay with you for if it were meant to be they would still be with you. (I can't take credit for that, it was Tony Robbins, loosely quoted)