How do I let go of my job stress after work and stop the things that are causing me stress?

I was thrown into a position without much training for the job and my bosses expected me to take on a supervisory role. Over the past year, while I've been learning, my strongest co-workers have left and hours have been cut back on my support staff. The duties keep piling up and I am now doing the job of my superiors for not even close to the same pay. This week has been particullary hard because everyday my managers have a complaint about my teams work. I work in television and everything is driven by ratings and one day this week the ratings were completely wacky. My managers are totally picking apart everything and I don't know what to do anymore. I have proven myself, and yes we are having a bad week on my show, but I feel like something is going to give and it's going to be bad for me.