It sounds like there are several issues here, and although I'm sure there are connections between them, they really are separate. As others have said, it's wonderful that you're taking care of your health and trying Weight Watchers, but your weight is not the major issue in your marriage or the reason for your husband's drinking. So continue to do what you have to do to improve your health and self image, but don't fool yourself into thinking that if you just get the weight off, your husband will suddenly turn into someone else.
Your husband's driking is HIS separate issue. He is not going to stop drinking if he gets a good job or starts communicating with you more. In fact, his drinking will probably make it harder for either of those things to happen. It sounds like he's depressed or has low self-esteem or both, so he's probably going to need to work on those issues himself. Encourage him to get help, but ultimately all you can do is get help for yourself. As others have said, try Al-Anon.
As for the marriage, the best advice I have is that there is a point -- or two or three or four -- in every long-term relationship when one or both partners question whether this is the right person for them. Couples who make it to happy old age together decided that they would be happy with the person they chose. You have to actively love one another -- love is not just something that happens to you, at least not for a long period of time. It takes work. And, of course, it takes work from both partners. So if you feel like things aren't so happy right now, maybe talk to your husband to find out whether he's feeling the same way and also wants to be happy with you again, even if just for the sake of your son. Then find a marriage counselor, join a church with a leader who inspires you, or find some other source of inspiration to learn how to begin loving one another again.
Mt. Calvary Lutheran Church in Acton, MA is having a special sermon series on how to stay in love right now. 9:00 Sunday mornings. I'm not sure whether this is near you or whether you go to church, but I am not particularly religious and yet find myself attending this series of sermons. I feel totally welcome there although I do not normally attend church, and the pastor is very motivational, so I'd reccommend that you (and your husband if you can get him to go) attend if you're in the area.