You really got me thinking here.
Have you heard of saying that path to hell is paved with good intentions?
I have seen two major categories of "asshole bosses":
1. The ones who don't care. These are in it only for the paycheck and maybe they want to see how far they can take it before they get sacked.
2. The ones who care too much. They want to be successful, they need to be seen as good example and will work themselves to madness trying to prove a point. They are also trying to achieve some ideal of their own, for which they feel it should not imposed on others. They think that they are running the show, but they rarely realize they are riding the wheel. Until they just cant take it anymore and drive everyone away.
There have been many people in your shoes. Arguably everyone who is in charge of other people has to face this situation sometimes in their career/life.
Perhaps you have read this essay from Derek Sivers, if you have not it might help you open your eyes and he even offers a pretty good strategy for dealing with your situation (http://sivers.org/delegate).
You say that you don't want to impose on your colleagues. What if there are some that want to be imposed? Who will leave you just because you didn't give them a chance to go through what you are going through now?
There might be people among them, probably most of them, who are willing to help you and have no need to see you suffering. For mutual benefit. They might help you if you are willing to admit the situation you are in.
I really hope you will be able to work it out. Go take a break. The world can do without you. Really. It will have to deal with you leaving one way or another.