Did Newt Gingrich's Wife Commit Adultery Too?

I was listening to a discussion about Newt Gingrich's conversion to Catholicism this morning and it glossed over the fact that he was with his current wife before he was no longer with his previous wife. It is clear that he committed adultery, but did she? In taking his nuptial vows, he entered into a contract that he broke. Clearly, this is wrong. But the mistress who would later become his next wife, took no such vow. He entered into the contract with his previous wife, she has no relationship whatsoever with her. Does the fact that the man to which she feels a physical attraction is already married cast any moral obligation upon her when she never acted in a fashion that would give her additional moral obligations? If someone steals your spouse, you would be furious at both of them. You have clear moral grounds to be enraged at the cheating spouse. If the person who seduced your spouse away knew s/he was already married, do you then have moral grounds for your umbrage?