I think you need to relax. Its about the journey. Fluidity happens in relationships and I believe one has to allow for that. Give it time.
If you really aren't sexually interested in her then don't have sex. There is no reason you have to.
You could change the description of your dynamic too. Maybe you and you wife are in a vee? She being the hinge and you having a metamour. Is your wife sexual with your girlfriend? If so maybe she is dating a couple. If any of that is important to you then redefine. If it changes; redefine. Keep it fluid. Whatever works. Just don't do stuff that isn't going to work for you, damages others and damages your self.
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