Gosh, I'm worried that if you keep doing bootcamp with your knee so bad, you'll end up having to have it replaced.
Surely there must be other things you can do that don't stress your joints like that?
I think given your sobbing etc. that you may have set yourself too difficult a path, at least with the exercise. No wonder you're stressed.
I think it's important to put your weight loss in a high position on priorities, but that doesn't have to mean hurting yourself.
I'd go to the doc, have him or her evaluate your knee--tell them what you've been doing with exercise--see what they say.
Hang in there with the food... assuming it's a good, nutritious plan.