I read this fairly recently (couple of years) and when I went to lend it to my mum I couldn't find it in my bookcase and can't for the life of me remember what it is called.
There are two childhood friends, one from a well off background and one from poor. One goes to jail for something (I think) and when is released works in a fairground. The other is living a nice comfortable life with husband and kids. They somehow bump into each other and I think the truth about what happened to cause one go to jail comes out. I think the chapters jump from the past to present day and they have different names in the past and present, so you don't know which girl is which. I think it builds up to the moment the 'big event' happens. You make assumptions which are then proven wrong at the end (hence why it was such a good book).
I thought it was the ice cream girls, but it's definitely not that. I've read so many that they all get mixed up in my head! Help!