If I understand your correctly, it sounds as if your house ground system (possibly including the water pipes) has become energized. The coax is tied into the ground system of the house.
This is very possible if the common conductor that goes back to your electrical supplier has become compromised, AND your house panel ground conductor is poor or non existent (depends on house age etc.)
If this is the case, the electric supplier should come and take care of their side of the meter ON AN EMERGENCY BASIS.
It's easy to put a volt meter on the cold water pipe outside and measure to wet earth or wet concrete. If you show AC voltage, YOU'VE GOT A DANGEROUS SITUATION.