Take it as a compliment that she feels she could still communicate with you. You must have touched her in a special way during the 7 years you two were married to each other.
You were a part of her life story during the seven years you were married....that's a good chunk of time. It's not easy to just turn your back on time like that. Because she calls doesn't necessarily mean she has romantic feelings towards you. Maybe it's just nostalgia, or maybe you are just a good friend.....somebody she could talk to. She must not hate you. Even if she did meet Joe Wonderful, you were an important part of her life. You havn't asked her not to call, have you? Then she will keep calling if you allow her to.
If my Ex wouldn't detest me so much, I could easily carry a conversation with him. I don't hate him, but the problem is that the feeling isn't mutual. He hates that I divorced him. He can't even look me in the eye when he picks our kids up for his weekend with them. There are time I wish I could talk to him about everyday life.
You must be a very nice guy!!