Ack!
You sound like you're in a bad, bad way! You are doing too much. The End.
I can only recommend that you try to find a replacement on some of your projects. If you find a capable replacement sooner rather than later everyone will be better off. I don't see how in your current situation you'll be able maintain high quality work. This is the advice I would give any of my own students.
Your university should have a release to work program in place? Where they have to approve any outside work you do. This program is designed so that the faculty can make sure you do not find yourself in this situation of complete over-extended-ness.
That said- I have funny pens & pencils- they light up or have feather's or are shaped like Dracula or the Nutcracker or Barbie... I don't use them all the time- but they sure do come out whenever I need a quick pick up.
Stress can also be relieved by communicating your frustrations & anger with your peers. For example- on this forum! I also love to call my out-of-town non-theater friends who don't know any of the people I work with & vent, vent, vent! it's completely reciprocal, and as they don't know anyone in the theater biz I feel totally safe. Probably this is why Analysts are so popular in our culture!
And Finally a nice long walk, cleaning house w/ long music or spending some time at the local batting cages have always been fixes for me!