Where Did I Go?

All body weight work tonight:
Squats x30
Burpees x10
Pike Pushup x10
Hip Ups x10 ea side
Leg Lifts x10
Crunches x20
I did 5 sets of that stuff, but I forgot to time myself.
I'm disappointed, to say the least. Let's go through the reasons.
First,  I wanted to do V-ups instead of leg lifts, but aside from my core being pathetic beyond belief, it made my lower back scream. So I had to resort to simple leg lifts. Even the hip ups were bothering that one disc in my back. I was reduced to tears by set 3 when even the squats were feeling like there was an ice pick in my spine. But I went on. Because I'm tired of feeling like a whiny asshole.
Secondly, I made the mistake of looking in the mirror and seeing a stomach that's almost back to where I started. I'm totally disgusted with how I've let myself go. That's not to say I'm not trying to reverse it (again), but I'm still disgusted.
Thirdly,  I'm simply pissed off with myself for letting myself backslide. I used to do 100 burpees in a day, now 10 is a struggle. There was a day I did 300 crunches as a challenge and now 20 feels like torture. I've done something I promised myself I wouldn't do and if I could kick my own ass I would. 
Now that I'm pissed off, saddened, frustrated and winded, I'm going to gave a dinner of tuna steak and rice.  I may be deflated, but I'm not defeated.