I can't relate to the OTTB side of things, but certainly can to the recovery from a tendon injury. I went through this with my youngest fella (who recently had the snip but was a 4 yr old stud at the time) It can be very trying. He was on complete stall rest for the first month with gradually increased handwalking & eventually turnout. Smrobs is right about the differences in opinions on treating & handling such injuries. With mine, I'd have loved to let him be on turnout 24/7 but knowing him well, being calm & just taking it easy wouldn't have happened & he would have created more problems.
LOTS of grooming time, toys (Woodstock had more fun banging around empty gallon milk jugs than any of the horse toys I bought for him.) I got to the point where I'd sit in his stall and read the current issue of Equus out loud to him, balance my checkbook, did some carrot stretches, and clicker trained him to touch his nose to a cone, etc.
I also agree with the pain meds, it's better for them to feel some of the pain so that they don't get a false sense of being okay and hurt themselves worse. I'd also suggest getting him on an ulcer preventative as the stress of stall rest (plus pain meds) can lead to them very quickly. I'm not a TB person, but as I understand it they are already fairly prone to ulcers to begin with.
Life is like a camera. Focus on what's important, Capture the good times, Develop from the negatives and if things don't work out, Take another shot.