It's pretty much impossible to do self-employment/marketing type work without a consistently good mental/emotional outlook. You are already stressed which makes you less effective at what you do which lessens your productivity which makes you stressed. That exact downward spiral you described is a vicious cycle, huh?
I'd say that if you can't take some time off for something really fun (a trip or cruise, visit with someone you love, etc), then start doing something completely different -- at least part-time! Variety is the spice of life, and yours has turned to drudgery (I know. I'm there, too, right now. See my current question on Mamapedia -- the first one I ever wrote on here).
Let's go on a vacation TOGETHER! LOL
You can probably refinance your house right now while the interest is at a VERY low rate. Or downsize, but then you have to sell the house you have -- probably at a lower price than you bought it for...