Christina's House Spoiler?

i need a little help i just saw the movie "christina's house" can anyone explain it to me.. im so confused.
What happens in the end of the movie called Christina's House? Who is killing all the people? Tell me the spoilers, don't worry, I like being spoiled.

Spoiler alert!

Well Howie was released from the same mental institution that Christina's mom was in and he was sent there by her mom to kill her. At the end Christina kills Howie but then you see another guy is being released from the same mental hospital and is being sent to kill Christina by her mom again.