repairing plastic channel on rear interior panel

[Doug1]

what will hold this plastic together from behind? The cracks are along the curved piece that folds over the metal seam that you see when you open the door. I need something thin and strong that will be strong enough to hold it together from behind without peeling off. I can use some sort of fabric glued to the inside of the plastic channel but the glue needs to really stick to plastic and not peel off.