SPOILERS SPOILERS SPOILERS
When the bad guy gets away, it's never a good episode. If you go to the trouble to make a bad guy REALLY BAD, and then let him get away, why on earth do you think viewers would enjoy this crap?
TV shows END when writers get all stupid and crazy and think that somehow viewers are interested in building some yearly long bond with a crazy, psychopathic bad guy. The writers can go sit at home and dream of their favorite bad guys, if that's what they're into. But the rest of us want an hour of entertainment with a good ending.
This was not a good ending. This was not a good episode. Do better, or find another career.