Good luck Billy!
Take care of your body from now on , eat healthy and start exercising safely in the Gym with a bodybuilding routine when the doctor give a green light.
Start with rehabilitation program that include Dips and Pull-Ups for your upper body strenght and exercise like plank and swiss ball core exercise for your lower back and abs.
Start a cardio program that include at least 3 Powerwalk session of 60' minutes a week.
Most important eat healthy wholesome food diet rich in fruit , vegetables and lean cut of meat.
One more thing Billy : " Remove that ugly tattoo from your arms and in particular the stupid one in your back that say fuck you"!
When we are young we do stupid thing but you should not have to keep the stupid past wrote on your body for the rest of your life!
I hope the best for you Billy!