wow that sucks man, time to start your own business
That's exactly what you need to do. Form an LLC and make up some mailers. Work out of your house to keep expenses down. If you can remember any of your former employers customers they would be the 1st place I would send the mailers. Offer them a cheaper rate if they mention the flyer. Then get mailing lists from your local Chamber of Commerce office and send them flyers until you can get some phone book ads.
This is what I did 8 years ago and while money was really tight the 1st year I was able to collect unemployment benefits until it the business made money. Spend anything the business makes on the equipment you need for the first 6 months. That way you qualify for full unemployment benefits. You can find plenty of specialty tools for your field on Ebay.
There are some other sneaky tricks you can try if you want to "legally" get even with your old employer but I'd rather you PM me if you want me to tell you those.