Hello,
I felt bad reading about what you are going through... I 'm sorry.
The fact the you have become ”fat” has draw my attention. Did you mean it literally? If yes, then how about you try to exercise?
For many people is therapy, time for themselves, disconnet from the world, a hobby etc.
Try to go to a gym. The first days you will be embarassed, I know I was, my bf was, many people are. But you will soon notice that everybody does his stuff there and care not about you.

Also exercising brings health! Endorphines are released and the state of well being appears.
This helps me, especially now when I am going through a separation from my BF.
Give it a try. You seem stressed.