help, I'm looking for a book. In it, people have died and somehow see how

[Heero]

life would have been had they done? in it, people have died and somehow get to see how life would have been if they had done one thing different. They have to do a kind of charity repent thing and then I think get to go back to just before doing the one thing that would have caused them to avoid death.

I recall one instance a woman was given money to get new tires from her parents, but bought a dress instead. She and her son died in an auto crash. There was a young teenage girl who I think was a cheerleader and she caused her family distress once when she changed out of the clothes she died in and all they could see were moving clothes. I think she was the narrator. In their "death" she falls for a teen boy she once passed on the bus which led to her car crash I think. In the end, they both released red balloons and instead of crashing, she sees the balloon and feels emotions she doesn't know why she feels them though.

I know that is not a lot of information. I read this quite a few years back, but if it rings any bells, please post!

Thanks!