I remember watching this as a child and it was so scary to me. No that I'm older I have a great understanding of why. It's not a gore fest, but more of a fear of the unknown. I guess what I'm getting at is still to this day if what Ben saw was all in his head or that house was so full of evil and death it was doing everything in it's demonic power to destroy everyone the inhabited the structure, so it could basically self-destructed. It's like a parent selfishly killing their own family before they kill themselves.
My personal note on how I perceived the film.
I find anyone that decides to commit suicide is a coward and selfish. They don't know how many lives they are effecting especially their parents, loved ones and very close friends that now are left with the saddness and heartbreaking thought, why didn't they just ask me for help if they felt that this was the only way out. And you certainly don't have any right steal the life of your own children?? As an adult male your job once You take on the responsibility of being a family man. You are to care, protect, and guide your children to have an amazing life full of happiness and strength. And if you have made that vow to your wife even if you decide to separate you never stop making sure she is protected and always knows you will love her and be there for her whenever called upon.
So my point is Ben let his own issues and self-pity distract him from what should have been the most important thing on his mind and that was the importance of his family. And he let it all fall apart in front of him.