Hi there ~
Your being upset, confused, depressed and frustrated is understandable. The surgery that was expected to make your life better did not actually turn out to be so. However, you need to look the life before and after surgery. You describe everything after surgery and how your knee should have been and how you should have walked, etc,. However you do not mention what you expectations were and how your life or your problem knee was before surgery. It is very possible to feel depressed, however you need to reconcile with the fact that the surgery and the consequent improvement is gradual and it should have been alluded to by your surgeon. I feel like you might need to be seen in personal consultation by a psychiatrist
or a counselor. I hope you feel better and that this helped.