Depressing leading to..... PLEASE HELP?

I've been severly depressed for a while. My father ped away in March after a long painful experience w cancer. A month ago I found out that my husband is seeing another women & a week ago I found a letter to her confessing his love to her. The past month I have lost 25 pounds. In the beginning I tried to eat, it would just come right back out. Ive been starting to eat more, but when I do my weight drops even more. I am 5'5 and only 110 pounds now. The doctor has me taking 150mg zoloft a day. But the amount of weight I am losing so fast is giving me many other physical symptoms such as sharp pains in stomach, vision, memory problems, shakiness, not sleeping, can concentrate. Im not hungry I'll have 1 bite and be in pain. My husband & I are still living together he is trying to decide what to do. I can't afford to move out & he wont leave. I fear this is killing me literally. I have a 2 yr son to worry about. How do I get this to stop & be able to eat again? What is going on w me?