It IS a vicious cycle. Depressed, eat, overweight, depressed about being overweight, eat, depressed. I'm all too familiar with that.
But, reading through your post it got me to thinking... you liked certain activities when you were younger.
Why not pick them up again? Or try a new activity? Something you can ease into and get to enjoy?
In most people activity can actually help to increase the release of positive chemicals in their brains. Not that some people don't actually need medications, just that movement may help in its own way.
I still remember the phrase HALT! To deal with emotional eating.
Are you Hungry (true hunger)? Or are you Angry/Lonely/Tired?
If you aren't Hungry - find an ALTernative.
I know it's silly, but I still use it to think before I go for the fridge. I don't just stick to angry/lonely/tired, either, but rather "Am I eating for emotional reasons? Yes? Find an alternative."
Making small changes and building up habits really has helped with my mood in general. Making time for movement especially.
One step at a time.