I watched it a few years ago.
The plot, as I remember it:
A family(Father, mother, 2 young kids) goes on vacation to a recently purchased house.
Father possibly has some troubles with job.
While travelling they meet his old school friend with his girlfriend.
This guy is possesed with the idea of the "father" of becaming writer, as he was good before.
They are invited to go with the family.
His girlfriend wants a baby. He doesn`t.
He thinks that his friend(the father) will write better if nothing disturbs him.
So he kills his girlfriend and then tries to kill "father"`s family with its own help, but the father kills him, hides bodies and then lies to his wife that they left.
Actually, by the moment he started to write again (something called "the eggs").
Does it remind you something? Thanks.