Husband not prepared to issue a divorce

My husband is an alcoholic and separated from the past four years. He is not willing to give Talaaq nor accept Khula. We approached many ulema, still no results. He doesn't come for a discussion when masjid committees call him, doesn't respond to the masjid. I need advice and guidance in such case where husband is not willing to release even if I am ready to give back mahar. He just harasses and give troubles. He is an alcohol addict. He will be missing from the house for months together, some one has to find him and admit him in a de-addiction center. Again after a month again he goes missing, even now he is missing. I can produce the medical certificate regarding his hospitalization at alcoholic de-addiction centers. If I approach through court and lawyer, it is a burden I can't bear. I have a 5 year old son too. Need guidance in such a case to get out from this marriage.