Dear Janice
I had to write after reading your message. You are NOT overreacting and you are NOT jealous. Over-reacting, jealous...this sounds exactly like what someone like your friend would say to try to make it look like it is YOU with the problem when it is their behavior that is wrong. I don't believe that she didn't know the cards were inappropriate. Even if you gave her the benefit of having not known with the first one, then why did she continue to send more cards after you told her it bothered you? You say you can't find anything to indicate that he is calling her or sending cards to her. But there is something he isn't doing that he should do and that is to tell her to stop contacting him. If he isn't willing to do this then I see lots of red flags going up. Especially since he already has the history of cheating. If he really cares about your feelings he would not accept any more phone calls and should not open any e-cards he gets from her. If he is not willing to do this for you I would seriously question this relationship. It isn't worth it if he does not give top priority to your feelings and well-being.Also, you certainly don't need this girl for a friend. I'd show her the door really quick, and if it hits her in the butt on the way out..well, she deserves it! You sound like a good hearted person. You deserve so much better for yourself.
Julie