So, basically you have such low morals that you will not respect the fact that he was already in a relationship before rekindling yours, that you think this kind of behavior is OK.
Pretty much, you're the other woman wrecking a relationship because you don't have the balls to stand up for yourself, and what is right.
"Well, then," the Cat went on, "you see a dog growls when it's angry, and wags its tail when it's pleased. Now I growl when I'm pleased, and wag my tail when I'm angry. Therefore I'm mad."