Heather,
If you can't untangle it, I would tie it off above the cut near the belly with a piece of unwaxed dental floss. Then cut it about half an inch from the tie off. Bruce Whitehead had a similar thing happen. See this thread:
http://www.ball-pythons.net/forums/s...ight=umbilicus
Of course the other option is to find a herp vet if you don't feel comfortable with it.