You sound as down on yourself as I am on myself. This is the disease talking. You are just as valuable as anyone else. My advice and what has been helping me so far is AA (and I'm not even religious), THERAPY (stressing that one), medication (mine for anxiety and also I'm on Antabuse - everyone is different), and reaching out to people even when I don't want to pick up the phone.
Since you don't have to work, have you thought of volunteering somewhere? Local hospital, humane society, etc. I was a stay-at-home-mom mom for several years and it's very isolating and can actually decrease self-worth in many cases.