I seems the chat didn't work correctly. My apologies.
First off, you're not crazy. Not one bit. Cheating is cheating whether its with a man or a woman, and whether its oral sex or not. Ask her how she would feel if you had oral sex from a man or a woman, would she consider that cheating? The problem is, the media bombards us with images of female bisexuality and lesbianism, they make it seems sexy, cool, the thing to be, that ALL men love it and welcome it with open arms, and that it's not cheating. The fact is, if it has a negative affect on your marriage, or your partner feels like they are being cheated on, then it is cheating....whether she wants to admit it or not. It is hurting you, you don't like it and she is being intimate with another human outside the realms of her marriage. You're not crazy.
I welcome your thoughts, let me know if you want to talk more