What do you do in the summertime when... you have just been ripped off?

In the past few weeks I have been ripped off not once, but twice, by clients. I was hired to do a specific job for a specific amount of money. I performed both jobs not just well, but very well. Both clients expressed satisfaction and appreciation for the well done work.
And yet neither has paid me.
I am in the process of taking the proper steps to recover what I am owed. In the meantime, I'm left with the emotions that come with such dishonesty. It frustrates me to no end that people do this sort of thing. Why would you hire someone if you have no intention of paying them, unless you really do have dishonest and quite frankly immoral or evil intentions? And how can you live with yourself?
To say the least, the dishonesty of these other parties has had a very negative effect on my life. I am a freelancer. I depend upon the work I do to make the money I need to support myself. When someone intentionally hires me, accepts my work, and then doesn't pay me, it isn't just some mere inconvenience. I don't have other forms of income coming in. It's the money that was supposed to pay for my food, shelter, gas, etc..
When I go into job interviews for full-time jobs I always get asked, "Why do you want to leave self-employment?" (Actually what they almost always insensitively say is, "why do you want to get a job now?" Because apparently working 50 hours/week from home isn't a real job.) The answer I want to give is, "I'm tired of getting ripped off by my clients, and I'm tired of working three times harder than I have ever worked before to make 3 times less money." But that is not considered a professionally appropriate answer, so instead I say, "I miss being part of a larger, dynamic team." (But I'm always thinking, "I really want a consistent paycheck every 2 weeks.")
So help me get back at the guy who hired me to write a 25 page e-book (10 pt font, single spaced) on how to use Facebook for small business marketing, and then didn't pay me, by buying, "Increase e-Book Sales with Social Media Marketing." It's not the same exact book I wrote for him. (I'm still trying to be somewhat honest. I said I would write it, he would pay me, and he would own the rights to the book. But since he hasn't paid me, I've made some changes, and decided to sell it direct myself.)
It's just 99 cents to buy.  Use this magic little linky straight to PayPal, and I email you the PDF (or .mobi file if you prefer) book right back! (I swear to you this is a totally safe and secure link!)

PS- I don't say too much about my job hunting efforts around here. It's considered unprofessional to do so. But today I could just use the moral support from my friends.
I was interviewing last fall for some jobs, but nothing really panned out. I took a short break from looking, but have resumed my efforts again. In the past month I've had 3 really big disappointments. 3 different opportunities where it came down to me and one other person for an ideal job. And obviously in each case I didn't get the job.  I'm reaching the end of my "able to handle so much rejection rope." (couple all of that with clients ripping me off, and you can start to get an idea of what it feels like on my end of this internet connection.)
Last week I had a job interview that was just... ridiculously bad. The interviewer talked about random, unrelated subjects for 20 minutes, and then said, "So you really aren't a good fit for this position. Why did you apply?" And this is after I have just spent 5 hours in a car to drive to the interview, not to mention close to $80 in gas for the travel. And that was the only question she asked me. She couldn't have asked me that over the phone and saved me the trouble?? Ugh...
Back to my point... I have [another] interview this week. And this job (what little I know about it so far), really does sound perfect for me. I'm excited about it. I am a very good fit for the position, and it is something I can see myself doing for a long time. Can you think some happy thoughts for me? Hope for a good interviewer who knows how to ask the important questions, and that the 500 crucial details I have to get worked out between now and then all come together. (Just one of them being getting paid!)
Thanks. I appreciate it.
Hmm... you know what? I just might go publish the Facebook for small business marketing book too. I can't really think of a good reason not to.