Need some pro advise....

[JMBT]

Last night was a BAD night. We left out from my brother’s house yesterday headed for the east coast with our new trailer on its maiden voyage. Everything was great for 940 miles. I had been checking all of the systems regularly, coolant, oil, trans cooler...etc since brother and I had had all of them apart for the vibe dampner replacement. Everything was operating as intended with no leaks. I was also hand checking all the bolts we had removed and retorque and all were tight.
Then about 2 am, I had been sleeping for about 2 hrs and my wife was driving. She woke me up saying that the battery voltage light had just popped up on the dash. I figured the alternator had probably taken a crap on us since it is original at 635K. She hit the shoulder and I hopped out and flipped open the hood. The main fan belt, (brand new), was shredded. And all 12 of the bolts that hold the vibe dampner and main pulley to the crank shaft nose had came out about 3/8” allowing the main pulley to jack sideways and explode the belt.

Now, what would have made the bolts all come loose?? I torqued them in a star pattern as Cummins suggested to 129 ft/lbs. I did antiseize them, but figured that would be fine as Cummins reccomended lubing them with engine oil during assembly. Was it the antiseize?? A faulty torque wrench?? What do you guys think?

Next question, when we hit the shoulder the coolant temp jumped to about 240 degrees. I had to shut it down hot because we had no fan or coolant pump, as the man belt was gone. The ECM logged a fault for coolant over temp at the least severe level. But what should I be looking for in the way of damage due to shutting down with ultra hot coolant?? Also EGT were around 500 when I had to kill it. What could this have damaged and what can I check?? The coolant temp dropped fast as it was about 30 degrees out and after I made the repairs the truck was running fine.
Today I pulled it all down again. Took the pulley out and inspected it for damage and it looked fine. I cleaned off the antiseize from the bolts, applied blue 242 loctite and retorqued all the bolts to 129 ft/lbs. I am parked tonight but will check the bolts with the torque wrench several times on the rest of my DH tomorrow.
Any ideas you guys might have for things to check will be much appreciated. Thanks.