Cannot remember a book I have read or the author

[Caroline]

Read a book about a girl who lived with her uncle and young daughter who attends college falls for the bad boy they have a relationship where he trys to get off with her as a bet. She falls for him and gets pregnant. Then we move on several years and she has had twins and is engaged to someone else and out of nowhere the bad boy turns up a man and unsettles her life. Any clues.