Yeah leaving wasn't a good idea, but as an i-banker, I'm sure your hours topped 70 or 80 a week (maybe even closer to 100). So I guess I kind of understand you. It's strange that you left voluntarily in this economy. I think from an adcom's perspective, it shows slight immaturity. Someone with a house, wife and kids would never just leave a job just to study for GMAT.
Anyway, that's just what I think adcom's would think. With only 2 years of experience as well, maybe since you are done w/GMAT, you should go work for another year or two before applying? If you must apply now, then just make up some reason as to why you left.
If possible, try to fill in any gaps right now with some volunteer experience. That way you can show you didn't leave to study. You left to pursue your desire of helping others. My 2 cents. Good luck.