The thing is, his mother won't get help if everyoen is enabling her... SHe won't hit rock bottom if everyone is enabling her... and hitting rock bottom is what usually motivates someone to cahnge... if NO ONE wants to be around them they eventually get the hint and change...
But, I think her getting help isn't that important.. I think your H getting some is higher priority.. I thought maybe since he is wayward right now you trying to make amends with his motehr may offer some incentive...
If you want him back, clearly for this guy getting on his mother's good side is the way to do that.
