Your husband’s drinking and your “controlling” is a signal to the two of you that your marriage is in trouble. Your husband is distancing himself from you and the family and is numbing himself with alcohol. You are right to be scared for him and for the future of your family.
I’m sure your home is a very lively place. The constant togetherness means that neither of you gets a break from the demands of work, parenting and household tasks. A child with Down adds a layer of stress and responsibility that most people don’t have to manage.
Do suggest to your husband that the two of you might benefit from some couples counseling. Sixteen years isn’t something to throw away lighly. Your kids need you to stay together if you possibly can. A counselor can help you figure out how to carve out some time for pesonal interests and friends and how to find time to renew your connection to each other.
If your husband refuses to go to a counselor, start with yourself. A counselor can give you some support and may be able to steer you to some additional sources of help for your youngest. If you haven’t already, do find out if there is a local support group for parents of children with disabilities. There is nothing so affirming as talking to other parents who share our experience. The challenges of meeting the needs of our kids with special needs, responding to the very legitimate needs of their siblings, and taking care of our own needs for adult connection can be daunting.
I wish you well.