Work is currently shit for me (excuse my french).
Maybe not as bad as your sounds, but pretty crap.
The thing you have to remember you dont live to work, you work to live.
Whatever happens at work its still important to do the things you want to do.
You only get one shot at this life Jimmy, so look after yourself and switch off when you leave work. I need to learn to relax and switch off and do things for ME.
At the moment losing flab is important to me. I am getting more pleasure from doing that then eating rubbish. Its a good change and is worthwhile.
Try and stick with the diet/exercise when things are tough. Its worth it. Good luck.