Wow, this started 6 years ago. I have been a one person training department most of my career and am now a freelancer still on my own. I like what you have written here and really agree with it. This is pretty much the issue with being in any business on your own, you have to do everything so what do you do first and when? I am happy that my clients know that I have other clients and respect my time. I have been fortunate to have projects that are due at different times so I can get the schedule right.
The other thing to add is to take time for your self and others you enjoy being with. If you don't handle your own stress, it can be bad. Have other interests as well so you don't have a one track life. Get out and be with other people so you are not working all the time.
It also helps to have a network of people even if it is virtual and to follow other developers online. They can provide help and solutions when you don't know what to do. The Articulate Community is definitely one of those places.