I sure hope you're getting along better, fireman.
Ahh, so no face cut. Part of the problem.
Anyhow, here's various ways to prevent what happened.
Make a small face cut, but open. Then bore cut to establish a hinge if there was room. Next, cut out the back.
Or, instead of making a backcut parallel to the hinge wood, make 45 degree cuts, with the apex directly behind the hinge, and cutting out the corner wood, ,first one side, then the other.
Those methods might have worked, but with all that lateral weight, the tree should have been ratchet strapped or chained, both above and below the cut.
Alternatively, perhaps this would have been a situation where the Coos Bay cut would have worked. Having never used it, I can't speak from experience. But, it entails making two kerf cuts, 90 degrees to the intended fall, then cutting from the back, with no face cut at all.
Methods for choking off a lanyard and lifeline can be simple. One on each side d-ring could have worked. Each line would have needed to have a friction knot that would give if the tree split and lengthened the loop.