Belt squeak and engine shake lead to no start

[Landrum24/7]

I have an 05 XLT that I take out mudding, rockcrawling and whatnot occasionally, I never run the hell out of the engine and I don't put me or my truck in situations that might end in compromising my vehicle. That being said about two weeks ago I began to notice some squeaking from the belt, it started out as an occasional in rhythm sound. Eventually it became an ear splitting squeal so I decided to look into it. I first replaced the idler pulley because it is cheap and was a possible source as well as the belt,which I replaced with a gatorback serpentine belt. Neither of these silenced the squeal and I caught on after a belt slip at the power steering pump that it was the issue. I wasn't immediately concerned with this until two nights ago when I was turning into my neighborhood and the belt threw from the harmonic balancer, I believe because of the play in the power steering pulley. This was an annoyance since the belt would not stay on the balancer every time I attempted to start it but I figured this wasn't a big deal, I could make it less than a mile without a belt, I thought wrong. My truck started momentarily, long enough for me to watch the oil pressure dwindle to nothing and then shut off. Now my truck will not turn over and I have no idea what the issue is, it is currently in the shop getting a new power steering pump but the mechanic is just as confused as I am about the no start issue. Has anyone had similar experience or any ideas as to what this could be?