Oh mama! That must be miserable. My only day to day advice it to try to rise above it and attempt to remember why you are there (for your family). Its hard to find work while you are working, but there's been a number of publications lately that places are hiring currently employed folks over unemployed, so you might be a higher ranked candidate if you did start applying elsewhere.
Could you have your family write good things about eachother on a peices of paper as a craft and then take in the ones about you to put in your office...that way when you feel yucky you could read them...
I also have my clients create a "smile file" for work. Put things in it that make you happy, a card from your husband, a picture of your family, a leaf from a walk....you get the picture....when things get less than smiley at work you go through the smile file.
Also, you could write the name of the instigator on the bottom of your shoe. All day you will be walking all over that person without him/her knowing! Like your own personal revenge.
If you can leave for lunch and go somewhere that makes you feel good, DO IT!
Good luck mama