SheFly - I don't have a torn rotator cuff injury, but am currently undergoing PT for bad tendonitis, er something. The guy in the cube next to me (also a cyclist), somehow did a slow speed crash (he fell over in some sand/gravel), and wound up needing surgery. They started with PT, then did surgery, then more PT. Shoulder is much better post-op.
I've only had a few sessions of PT for my shoulder. Parts of the sessions are quite pleasant, and parts I could almost scream. Of course I want it better NOW!, but these things take time. I'm scheduled for a month of therapy. What I need to ask is how soon I can get back on my bike. Have been a slug, and am afraid of doing more damage since I can't point to a specific accident that messed me up. Somehow mine are cummulative impacts (and age).
So good luck, hope you get to feeling better, but unfortunately, these things take time. And if it's torn, surgery may be the only way to go - have to pull the two pieces back together.