Spoiler Alert:
I have completed Alan Wake. I have talked to other friends who have completed it, but I still do not know what happened.
Did he sacrifice himself for his wife? If so where does he go?
Here's a little article that goes to explain the ending of Alan Wake. Hope it helps.
Here's an excerpt from the article
Another important thing to notice at the end is that Alice survives. The story is pushed forward by Alan thinking that he's lost Alice in it turns out that she survives, when she clambers onto shore having almost drowned. She's calling out for Alan, so he's apparently nowhere to be seen.
So what has become of Alan? This ties back into what was said earlier, that Alan is the one who sacrifices himself to ensure Alice survives. Slightly barmier theory doing the rounds - Alan Wake is happy to take the place of Tom Zane because he is Tom Zane's son, which explains why Zane knew so much about Wake and also fits Alan explaining that he never knew who his father was. Hmmm...