Don't throw away this precious entity. In complete darkness unravel about one foot and, in the dark, load that into your camera. Take pictures and develop (in a tray if easier: Dektol is fastest for this test), just to see what is what. If this end has escaped destruction, you are probably fine. If not, take off another foot and do the same.
You did not state whether you SAW film, just that the bag was not sealed. Was the bag folded over? You are probably safer than you think. The trick is to find where on the roll is the place that is past the possible lighting damage.
Ilford does not (or, for you Brits, 'do not') provide cans for their bulk loads. - David Lyga