Life has been downhill, now for the climb back

My name is Scott Cruse. I joined the army in 1998 weighing a staggering 110 pounds dripping wet at a skyscraping 5' 8". Double rations for 15 weeks had me at my "fighting" weight of 178 pounds. I was 17 years old. 14 years in the army, and raising 2 children on my own have taken their toll on me. I am now disabled and the years of service have destroyed my back and knees. I tried to maintain my health and teach my kids healthy habits, but, at long last I went to my Doctor this week and was informed that I am dangerously over weight, my liver has fat deposits, I have a BMI of 36+, and this is even after I quit smoking 6 months ago. It was a real wake up call and I hope to try and get myself back to that 178 pounds so that my kids will be able to play with at the park again. Walking / running is unbearably painful due to my fibromyalga, I live in the mid-west so no year round pools for water exercise, and being disabled on a fixed income i can not even afford a gym membership. Hoping to figure out a diet and a health plan that will help me reach my goals. 60 pounds by August 26th! Thanks for reading and wish me luck!