I Feel Like My Fiancee Still Has A Back Up Plan

So my fiancee and I just got engaged last month, and I found out recently that she is still talking to her most recent ex, let's call him Joe. This wouldn't bother me in and of itself, but apparently she talks to Joe a lot. In fact, even though Joe is safely far away, she talks to Joe almost as much as she talks to me. Joe IMs her several times a week, calls her hun and dear, and their conversations are very emotionally involved, too much for my liking.

She shares essentially every detail of her life with J0e(except our sex life, thankfully). I think it is safe to say that emotionally, Joe is certainly a rival.

However, I also found out that she was sleeping with Joe still as soon as a week before we started dating, and that she lied to Joe about our relationship and claimed that it began a month after it did to avoid "hurting his feelings". She says that she'd never cheat on me, but I can't help remembering that she slept with Joe after she slept with me and kept doing it right up until we started dating, while all the while she was the one pushing for a relationship!

I'm very uncomfortable with her having Joe as such a close friend and now she's told me that she wants Joe to have a prominent role in the wedding. I don't think she should be talking to Joe let alone inviting him to the wedding, am I too jealous or do I have a point?