1996 Nissan Altima Hidden radiator problem causes blow up

I swerved to miss a deer in my KA24DE Altima and took out a sign, but drove it home fine. The next day (3 days ago), It overheated after being driven around town for about 20 minutes, and I discovered a crack in the plastic head of the radiator behind the cap, maybe 4 inches long, and there was no coolant in the radiator or the overflow. I picked up some plastic-certified JB weld, vigorously cleaned the spot, refilled with distilled water, and everything worked great until last night. I checked the next day and the coolant level and epoxy seal looked good still.

I was driving on the freeway at 70 for about 15 minutes when I noticed the temp gauge was a touch higher than normal. I dropped off cruise control, and the engine dragged MUCH more than normal. Under throttle it was knocking like mad, but off throttle at sounded normal. I dropped the clutch at 55 and the engine died instantly. CEL never came on until then, and the temp gauge was high but not much higher than it had been moments before. The bay was smoking a moderate amount when I got out. The epoxy seal on the radiator was broken and I noticed a large oil spray around the pulley side, covering the alternator, coolant overflow tank, probably the whole pulley system also. The radiator was empty, but overflow was bubbling and full.

It was towed off the freeway by truck and chain, and I used a small amount of clutch for minute braking. The engine started idling after enough drag brought it up, and it idled fine, though it built up heat very quickly and I shut it off after no more than a minute of idle. I checked the visible portions of the oil pan and there was no damage, and because it actually ran without any unusual noise I can only assume all the rods are intact. Due to circumstances, I couldn't get a good look at the actual source of oil, though it is definitely from the pulley or car-front side of cylinder 1 judging by the places where it sprayed.

This engine has a cast iron block and apparently is very good at not cracking. It was burning a small amount of oil sometimes (mainly under hard throttle) before I ran over the sign. Other than that, the car ran like clockwork. I probably should have changed the oil about a month ago.

Any help would be dearly appreciated! If its an issue with a gasket or the oil circulation system I won't invoke insurance, but the likely hood of serious internal damage seems high, in which case I would.

Thanks!