I just got caught up on your thread. Your name caught my eye! LOL
First I just want to say I am sorry you are here but it's a good place to be in your sitch.
You have received a lot of good advice. I hope you go back and reread some of it again until it fully sinks in.
Would you mind if I put my 2 cents in? Well since you are here I am sure you don't mind, lol!
Mrs, if you are really serious about saving your M please don't go out on that date. You would be doing exactly what your H is doing...trying to find happiness on the outside. Happiness has to come from within. You can't rely on someone else to do it for you.
You need to use this time alone to focus on you. You need to find YOU and what makes YOU happy. Dating right now would only be a distraction and won't keep you focused. This OM is nothing but a fantasy, an infatuation. You can't save your M by bringing along the OM for a ride.
Listen, this ride isn't easy and it's most likely not going to be a short one. You can't rush it along by trying to make your H jealous or telling him that you are setting him free. If it is MLC then it will be done on his time, not yours. You can't make it move faster but you can prolong it. You can prolong it with your actions. IMO, I think dating will only prolong it, not move it along quicker.
I do think you have a good head on your shoulders and what I like about you is that you don't seem to get too defensive. You do seem to listen to what people have to say and learn from it.