I'm in the 7th year of a PhD (just weeks from submitting my dissertation) and wish I had dropped out at the end of the 3rd year when my supervisor disagreed with the direction of my work.
Whilst I can't help you - only you can make the final decision, I offer some questions which might de-fuzz your thinking.
Other than the motivation of prestige and possibly having "Dr" in front of your name, what excites you about computational biology? Does it still excite you? Do you enjoy reading the stacks of papers by other academics? Have you written any draft papers yet? Do you enjoy the collegiate atmosphere at your uni?
Anxiety is a normal part of the package of being a PhD candidate. Everybody goes through that phase. The bigger issue is whether you are still excited about the area of your research. If not, then it will only get harder to continue. Talk to your advisor, fellow researchers and other PhD students - especially those who have done a few more years and have had some papers published.
Do you plan to go for an academic job? If so, consider that competition is fierce and you will pretty much be writing grant applications and papers and teaching and only doing a small amount of actual research. And all that for a lower salary than a good software developer can earn.
If you are thinking of finding an industry job with your PhD, then what sort of jobs are you thinking of? Have you done any research as to whether your speciality will be in demand? Of course, you could work in a different area, e.g. Wall St (some PhD's in computational biology have made that switch).
If you decide to abandon your PhD work, then the best strategy is to continue from where you left off with your industry experience. If you have acquired any new skills in the past year, then add them to your CV. But otherwise, you might have to pretty much treat the past year as an adventure holiday. Whatever you do, don't expect any potential employer to put any value on your academic work.