Faith: My name is Don and I'm a recovered alcoholic blessed with 30+ yrs of sobriety.My wife, Iris, has been a member of the World Wide Family of Alanon for the same number of years. I asked her to read your post and give me some of her Alanon experience to pass along. She did and made it quite simple...you and your husband should get to Alanon and do something for yourselves regardless of what your son does or does not do. Secondly, she recommended you keep your commitments...if your son is still drinking and has made no effort to seek help, stand by the contract of having him out of your house by September 1 (should be gone by now). Last, when your son mentions he'll do himself in, isn't that what he is already doing by continuing his drinking. Nothing new there as the nightmare of your brother's death 13 yrs ago affirms that.
For my two cents worth, if he choses to continue to drink, put him out...always an empty doorway on skidrow that he can call his home. Why not..he sure does not appreciate what you have provided for him.
I've never attended an Alanon meeting but they meet down the hall from where my A.A. group meets and I see them leave each week after their meeting. Without exception, they all seem to be smiling and happy, I'm sure this could also happen for you and your husband. As they say in A.A., stick around for 90 days or so, and if you do not like what happens in your life, they'll be more than happy to refund those miseries you brought along with you for your first meeting. Good luck.