I'm sorry he wasn't sincere about rehab, and sadly I know how you feel.
Part of the "pre-manipulation" performance my son used to do was "I have stayed clean today and made some calls to rehabs, just waiting to hear back from them now. By the way, I need to pick up some toiletries to take with me when I go, could you lend me $40?" It always seemed to be multiples of $20, and that was a giveaway every time. $20, $40, $60 = lies, lies, more lies.
It just shows us how very sick they are. Clean and sober, they wouldn't dream of behaving like that.
So we pray for them, because we cannot save them. I pray each morning knowing that God can do for my son what I cannot. God's just waiting for my son to ask. Even God doesn't interfere because He's not a codie.
Hugs