confused about the ending...

Here, let me help with your confusion.

His name is Luke Wilson.

Heh. Actually it's a bit open to interpretation but here's my take on it:

SLJ's character seems to be the embodiment of evil - hence the movie title. Now he turns out to be a hired killer but I think there is more to his 'evilness' than just that and I think the whistling is part of it. No one knows how this character became this way but my theory is that he, his mind/body/soul/whatever, became possessed by 'evil' - a demon/the devil/whatever - at some point in the past and when he died at the end this 'evil' presence jumped into LW's mind/body/soul, hence the whistling at the end.

Now it could all be a bit more subtle than that and this whole 'evil' thing is metaphorical and not literal. You know, acts of betrayal etc beget anger begets hatred blah blah blah - you know the drill. All the *beep* that got poured on poor Luke with the final big fat doody being his wife's infidelity and her trying to have him killed just made for a bad day and he became an evil dude as a result.

But whatever - it's really not interesting enough to warrant even this amount of thought. T'was a generally poor piece of writing and film making.

Hope that helps.

slj was hired to kill luke, luke kills him first and decides not to cooperate with the police when dealing with his wife, I guess he still has some feelings for her.

Not really that difficult to understand

I dont think there is anything supernatural in the movie, like slj being possessed by the evil.

luke was cheating his wife, full of debits, and the wife was having an affair with the pool guy, she planned to kill the husband, get the money from the insurance and continue living in her dream house with that guy.

In the beginning we see in the mirror slj car passing at the same moment luke is talking with the pool guy, later in the movie slj reveals the wife used someone else to contract him to kill luke. Its implicit the pool guy hired slj. Also, sj knew their names.

Now, its clear slj went directly in luke's house to kill him, but the little girl presence was inconvenient, so he grabs luke and somehow his psychotic twisted mentality become attracted by his target.

At the end we see luke having to deal with his wife, he just dont trust she anymore, but was not certain if she was able to contract a serial killer to kill him. he is confuse.

and the movie was bad directed

It's pretty explicit. The wife had someone hire Jackson's character to kill her husband, because she was desperate. That's how Richie knew his and his wife's names. Ironically, Wilson's character, John, seemed to be contemplating suicide as he gazed into the unfinished pool like an open grave when Richie came knocking. Richie apparently observed this contemplation off screen and it bothered him. Being an unhinged individual he went about trying to 'solve' the issue that was nagging him. He wanted to open John's eyes and show him 'the world is evil' and he wanted John to accept that and become part of that world-view...then presumably kill him.

Richie is a sociopath and his reasoning is a bit obscure, but I think he stumbled upon John as he was about to off himself, and it made him think twice about the hit. He probably isn't capable of feeling sympathy, but something akin to it that confused him and prevented him from killing John and motivated him to educate John and lift the veil and reveal the world for what it is.

Never read the book, but here's the problem I had with the movie: the Samuel Jackson character was a caricature. The Luke Wilson character was way too passive for protagonist. The wife had one good moment (when she reamed out the policewoman). There were no characters to empathize with and therefore no tension, especially at the end when (spoiler alert) the antagonist is in the house. As for the "whistling"... Some people think Samuel Jackson's character was a demon and it possess Luke Wilson's character. I'll be generous and say it's Luke Wilson's way of getting the gonads to kill his wife.

I thought it was pretty much what you saw. She hired Ritchie to kill John, he was extremely crazy, John was a wuss, and after all the %$#& hit the fan, they (sorta) lived happily ever after.

He was hired by the wife to kill her husband (that's how he knew his and his family's names, and why the wife left the back doors wide open and took the kids to the park).

He lured Wilson out to his car. He was supposed to kill him when Wilson fell down with his leg injured by the car exhaust backfiring, but there was a little girl watching them.

Jackson used that moment to decide taking Wilson along with his little killing spreed to 'wake' Wilson up. Jackson could have killed Wilson and the little girl, but he was intrigued by Wilson's seemingly broken spirit to "overlook" them.

When Wilson realized it was his wife who hired Jackson to kill her husband, the wife got nervous. He surprised her by not letting the police take her in for further questioning. She still wasn't sure if Wilson believed Jackson's story or not. She seemed to know that Wilson knew Jackson had told the truth, so his lack of reaction was unnerving her. I think at this point, the filmmaker wanted us to think "What is he doing? Is he really that dumb or naive? Or was Jackson's claim a lie?"

She was very nervous when they got into bed. She asked if everything would be OK, his lack of response was the first clue that something wasn't right (throughout the film, he assured or apologized to any response)

Would he - like Jackson had been saying: "turn back and walk away from everything" - pretend the whole thing didn't happen? Or will he do something about it?

We get our answer when he whistled in the dark. Wilson had every intention to kill his wife some day.

Remember earlier when Jackson said that he and Wilson were a lot alike? This implies Wilson's passivity all this time had been suppressing his "true self". This was partly awaken by Jackson's killing spree. The last nail in Wilson's coffin was his wife's conspiracy to kill him as it had effectively brought out Wilson's "monster". Hence, the whistling. I guess the film was trying to give a fresh take on a saying: "it takes one to know one"?

That's what I think, anyway.