How to balance feelings for the mistress

A month and a half ago, I began a relationship with a woman outside of my marriage. Before anyone crucifies me for that, please know that I am aware that it is wrong. I'm not looking for a lecture, I'm looking for advice. Anyway, this woman is amazing. She and I have a lot in common, are both very quirky, and are both attracted to each other. She knows that I am married and is fine balancing that in her life, as she does values her independence. We really are crazy for each other and talk nearly every day. The other day, she was shy to inform me that she had been "picked" to be someone's guest for a black tie event. She showed me the dress she will be wearing and it is beautiful. But now, I'm crazy jealous. She says not to worry, but how can I not? We haven't been able to have a nice, romantic night out yet. We've had drinks, coffee, dinner, and walks in the park. But nothing quite like what she's going to. I know it's hypocritical, but here she will be going out looking radiant with someone who clearly has more money and more abilities to date her than I. Yes, I love my wife, but it hasn't been great for years. The woman I have been seeing has helped me discover what it means to be romantic. And now someone else is getting that chance. How do I turn off this jealousy? Looking for advice from people who can relate.