Sorry that this happened to you, but if you steam it perhaps the batting will relax some. Or you could place a plastic sheet on your carpeting, lay a bed sheet on top of that. Dampen the quilt and place it on top of the bed sheet. Gently square it up and pin right through the sheets into the carpet with T-pins.
Lastly, if the quilt is pretty good other than the wonky binding, or at least that's what I can see in the pics, just redo the binding to fit the quilt's new smaller measurements.