Feels like failure

Ever since my last mile workout more than a month ago, I have been anxious to get back on the track and keep pushing. My previous workout was interrupted by some stomach pains, so I was left with a desire to see where I could go with a longer stretch of mile repeats.
I had my chance tonight, with 5xmile on the schedule at American's track. I finally met the elusive Matias who boasted the impressive (to me) resume of running with Scott Sehon, Greg Costello and Aaron Hanlon at Bucknell. Letting Karl, Jake and Dirk go ahead for their speedy miles, Matias and Andy and I held back and I led miles at 5:14, 5:12 and 5:10, with a 400 m jog between them, which I invariably took too fast. I had planned to run 5:16, 5:12 and 5:08, and admittedly, seeing 5:10 for the third interval was deflating. Matias led the fourth mile, but after 200 meters I was toast- I wasn't breathing quite right. I jogged the rest of the lap and put a long-sleeved shirt on (extra tight) and planned to run a few 5:20s to relax and still get some work in, but judging from my 43 at the 200 mark, I was done.
I keep in mind that I was still cutting time each mile and doing them under control, but regardless, I was awash in frustration and wondered aloud if I would ever break 16:00 for 5k again. I tried to run around a bit while everyone else finished their workouts, but I didn't even want to do that- I felt frail. Things picked up when we went for a cooldown run, but then I was cut from a Russian ballet troupe and sunk into a deep depression.