It's no wonder you feel discouraged and worn out. This has dragged on for so long.
As the others said, do go to see the revision specialist and see what he has to say. It may be that, looking at your knee with new eyes, he can see something that can be done to help. If you need to, ask him to write a few things down (I sometimes ask surgeons to draw me a picture, too), so that you can go home, assimilate what he has said, and then come to a decision.
You don't have to decide immediately. Maybe taking a break is what you need right now. Rest and refresh, but don't give up entirely.