try abandonment... "fraud" just sounds so awful that many people would be all over trying to defend it... look at what happened when Kenny Chesney was accused of "fraud" in the marriage... they filed thinking it would be best to call it "fraud"... not specific, just that they made a mistake & didn't realize what they were getting into... next thing you know, people are questioning his sexuality!
Be careful about throwing around the words "fraud" when she might take the opportunity to hurt you.