First song is the overall theme of the apocalypse.
Chocolate Helicopter - Left 4 Dead 2 soundtrack. Copout? Yeah, but it fits.

Second song is what plays when you kill your first zombie.
You know my name - Chris Cornell. This'll play on the roof of a building and start as I shoot a zombie with a revolver and it falls off the edge.

Third song plays when getting chased by a horde.
Doctor Who theme song, 2008 - Murray Gold... What?

Fourth song plays when you have to kill your loved one.
Dead Island theme. Well, that one from the trailer.

Fifth song plays when you find another group of survivors.
Never Far Away - Chris Cornell

Sixth song plays when you meet a new love interest.
Hand covers bruise - the Social Network soundtrack

Seventh song plays when you have to make a final stand.
Skin on our teeth - Left 4 Dead 2 soundtrack. Seriously. Look it up. Now.

Eighth song plays when you think you survived it all./Ninth song plays when you discover a bite mark on you.
The monsters within - Also Left 4 Dead Soundtrack. You know how it shifts tone in the middle from "YEEEEEEHAW! *Chainsaw noise*" to the darker more forboding tone? yeah. that.

Tenth song plays over the end credits.
Song of unhealing - BEN. Creepypasta. I dunno why.