I think rick addressed some good issues there and it sounds like you were in over your head. Having been there before myself please realize it isn't over for you. I got hired in 2007 with 300hrs at a chew you up spit you out regional and was ultimately unsuccessful when it came to time in the sim. Pretty much I was in over my head in terms of the airplane. After being let go I CFI'd for another 400hrs and networked my way into another regional gig. They had concerns about me getting through training and I was honest about the situation and emphasized what they experience taught me and how I would be successful in the future because of it (this was preColgan accident). They hired me and I made it uneventfully through training to the line.

That carrier had massive cutbacks in 2008 causing me to get furloughed. I since spent the next 2 1/2 years as a CFI flying 700hrs a year. At the end of last year I started reapplying to regionals and unfortunately found that a lot of my apps found the circular file due to my 121 incompletion. After some soul-searching about my career goals and some networking I've recently landed a 135 gig on a Hawker 800. Having just finished a PIC type rating on that plane, the regionals that would rather take a 800hr guy that has never been through 121 training rather than someone that has been through two can suck it.

Now how does my nonsensical rambling apply to you? Like rick said expect your next few years to be in 91 and 135 operations. Right now the 121 carriers are looking for ding free records after all the flack Colgan got for the CA's training record. I would expect if you put in a year or two of flying hopefully more advanced aircraft would better prepare you for future opportunities. I think regionals will be able to overlook it when their pool of pilot candidates starts drying up.

You never know what opportunities you may find. It could end up being the greatest thing that happened to you.