I won the lotto a few years back, and my life has fallen apart. Where did I go wrong? Was I too selfish?

I won over 16 million dollars. I went back to school and finished my degree in chemical engineering. I payed off all of my families homes. I helped my friends, worked with the homeless (they pretty much all took advantage of me), and started an organizatino to help tutor school kids. I also pursed a lifeling dream - riding motocross professionally. I never made it "big", but I had great fun. After a terrible accident I lost the ability to use my left arm. I started feeling sorry for myselft and it has been a downward spiral since. I haven't left my cabin in three months. I haven't turned my phone on for nearly as long. I am so lonely. The only time I am not in pain is when I take sleep meds and am not awake. Does anyone have any ideas to help me? I've got a good heart, I just can't figure it out. Please, I respect "believers", but I am not interested in finding "God", as I am very much agnostic. Thanks so much.