1997 Honda Civic Ejected spark plug

While driving on the highway under not much load ( flat land ) in 5th gear, my honda hatchback all the sudden launched/ejected # 3 spark plug. I immediately pulled off the hwy and seen that the plug had been ejected, a dented hood, and a some antifreeze had sprayed out from somewhere ( about 1/2 cup ). No smoke was coming out the tailpipe, it appears the antifreeze did not come out of the spark plug opening because there was no antifreeze on the underside of the hood next to the dent created from the spark plug ejection or on the plug&wire. All the threads on the spark plug were there, but all threads in the Aluminum head were fully gone. The GAP on the spark plug had been fully closed as though it was hit from a cylinder head? I know that you can cut steel with water, so with enough speed/pressure/& timing I'm sure anitfreeze could close a gap on a plug in the right conditions. The car is not worth much ( we're still original owners, & my dad was a Master Mechanic and taught me over the years as much as he could before passing away ) so towing it was not an option. I disconnected wire #3 and had my wife follow me home. Again on the flattest path home, which was approx. 13 miles, the car continued to start up fine and the other 3 cylinders seemed o.K. ) Except for the idle & crank balance. During this drive home ( approx 83 degrees ambient temp. ) The car did not run above normal operating temp, no smoke coming from anywhere, and the antifreeze leak did not leak again.
* Any help would be appreciated, Pops won't respond, via the other side. LOL. And I need some assistance now that he is in heaven and won't answer.
* What are your thoughts, besides ripping the engine down until I physically find out what happened?
* Also, is it possible that I may have blown the Head gasket seal on JUST #3, dump enough antifreeze in the cylinder on the down stroke, to crush the gap on the plug and then send flying into the hood? My first thought was the timing belt went, but that would have sent all the piston heads up into all the valves & spark plugs?

Thank you in advance,

The Grease Monkeys Son, Adam