I'm very sorry to hear about your knee problem (had the same diagnosis myself when I was training for a half-marathon back in the early 90s). The good news is that it will go away, with some rest and rehab.

Try to focus on the long term gain from the short term sacrifice. I agree w/Zen & Starfish---concentrate on your swimming and other activities. Can you row? I've found that adding rowing back into my training has done wonders with strengthening my core.

Sending you lots of good vibes for a quick recovery!!