Well, we have plenty of opinions about what to do after the rope suddenly releases, lets take a quick check on how to keep the rope firmly attached until we decide to release it. When you hooked up the rope, did the 'pull' feel normal? If it didn't take much of a pull, one of the springs in the over-center mechanism may have failed. Did the cable return all the way back into its tube? If not, broken cable strands may be flaring out and preventing the tow hook from returning all the way back to its fully closes and locked position. I have seen low altitude releases caused by both of these malfunctions.
Condolences to the family,
JJ