Spoiler... Ending Observation
I just watched this online.
At the end, Denise went to Karla's place for refuge (of course, Karla had already died from a suicide earlier). While she picked up the phone and tried to call somebody, Karla cocked the gun. Denise looked at Karla, smiled, then closed her eyes and was shot to death.
It's like Denise finally gave up and accepted her fate - to die with the rest of the victims.
Show me the holes!