Can I go swimming at this point to help me mentally
If you don't overdo it... sure!
Also the main problem.is that also I'm really struggling to be able to bend down to tie my shoe on my operated leg after 8 weeks post op why is this?
I just had to remind myself often -
Tightness is a normal occurrence after this kind of major surgery. Your surgeon did major carpentry work and disturbed every millimeter of soft tissue in this area. You aren't tight because your muscle is underused and needs to be stretched and rehabbed. You're tight because your tissue is healing... If a long full step right now is causing pain and limping, don't take long full steps. Take smaller steps. Take a short walk several times a day, instead of longer walks. Use your cane. Use ice. Rest a lot.
This isn't the time to do anything to excess. Baby steps now, and lots of patience, pays off big time later. Recovering from self-induced tendinitis can end up taking weeks or months. Consider yourself as still recovering from surgery and structure your return to your life as a slow, gradual process where you introduce very small increments in activity, and then give yourself time to see how you react to it.
All temporary, and worth the patience. I am certainly glad I am able to get back to a full happy life!
Question I'm now 8 weeks post op and still have knee pain but my operated leg has been made 3mm longer could this change in gate and the stress of surgery be causing the knee pain and will it settle down?
This very well could be!
I've seen this complaint many times so I guess you could say "Its normal "
Again, taking things slower for a few weeks may give you a lot of answer to your questions.
You have nothing to lose by backing up some.