If it involves the sex organs, it's sexual. If it's sexual, it's cheating. And the fact that it made you upset should be ample proof.
This is a test of your relationship. How you view each other and how you handle difficult situations. You need to have an honest heart-to-heart. Explain how and why you feel betrayed by her actions - not "you cheated on me" but "i feel hurt by what you did and because you tried to defend it". But give her an 'out' - the chance to make amends. In the end, it's not about 'right' or 'wrong', or whether she can justify it - in the end, it hurt you, and if she truly cares for you that's what should matter.
For reference, since people love to follow the Clinton route and bring semantics into it...Cheating, by definition, is being "sexually unfaithful" [dictionary.com]. Faithfulness involves "steady in allegiance or affection; loyal; constant; reliable; trusted" [dictionary.com].
This is a test of your relationship. How you view each other and how you handle difficult situations. You need to have an honest heart-to-heart. Explain how and why you feel betrayed by her actions - not "you cheated on me" but "i feel hurt by what you did and because you tried to defend it". But give her an 'out' - the chance to make amends. In the end, it's not about 'right' or 'wrong', or whether she can justify it - in the end, it hurt you, and if she truly cares for you that's what should matter.
For reference, since people love to follow the Clinton route and bring semantics into it...Cheating, by definition, is being "sexually unfaithful" [dictionary.com]. Faithfulness involves "steady in allegiance or affection; loyal; constant; reliable; trusted" [dictionary.com].