Man.... You're taking a huge gamble riding that thing to the corner, much less to Lima, with the sprocket in that condition. I'd arrange to store it and get your parts by bus. And I recommend NOT to tighten your chain the way you've been doing it. Keep it loose! Your sprocket / shaft problems and chain stretching are indicating having set the chain too tight.
Here is a diagram of a chain drive and swing arm - with a line between the sprocket centerlines passing through the centerline of the swingarm pivot.
To realize this is the tightest the chain will ever get, over the suspension travel, imagine the rear moving up or down from this aligned position. Since the swingarm pivot is between the sprocets, you can see that the distance between the sprockets (labelled 24" in the above image) will decrease to less and thus the chain will become more slack.
Hence, if the chain slack is set to a minimum acceptable value, just loose enough to not be under tension, in this case about 1/2" of play in the center of span, at the longest distance between the two sprockets, as above, then the chain will be properly tensioned for full suspension travel. It should be not sloppy but not under any tension in this position of max tightness.
I know you must feel terrible about pulling out onto the road when a car was coming. The great thing is you got off without getting hurt, not to mention getting off easy paying the guy $100 and not even going to cool your heels in jail. You were super-lucky on so many levels! God is with you, and here he was reminding you - perhaps you are not praying enough
Slow down a bit and focus, brother in spirit.