Hello Wanted, I saw that you posted on my thread so I thought that it would be best to respond here.
Do NOT get the MIL involved. Yes, I did do it but regretted it instantly as it was the wrong thing to do. I was not thinking clearly and although I got a reaction from it, I cannot trust the intentions. Did my W only reach out because her Mother talked her into it? That is not going to help my cause and it surely will not help your cause. There are some unique circumstances in my W's past that make the R between her and my MIL very important that I cannot really get into here.
Listen to the others her and GAL. As far as your question above about telling her what you are going to do and who you will be with, it is none of her business. You have a meeting out of town that is all she needs to know. Being mysterious and living your own life is just one of the many ways to potentially get a WW to turn her head and become curious. Let her be curious, you do you for now and not worry about her.