madscot, I know how you feel. Meeting bad people in traffic is such a confidence killer, and not wanting to ride really sucks...

If you can, try to make the next rides easy on yourself. Get up earlier (or go in later) to miss traffic, try to have plenty of time, try biking in with all the time in the world just to keep your pedals turning. Stop and have a coffee on the way. Have somebody ride with you.

Hope your knee and psyche heal well!