It doesn't sound like he wants to share said woman with you... I'm wondering what is behind adding the question at the end about doing so. There is no reason you would have to. It is a good idea that they know each other, and better yet, get a long, but it isn't necessary for her to be shared.
This sounds like something you have wanted and needed in you life and it sounds like your man is very willing for you to pursue it. That is great! Enjoy the ride and please feel free to let us know how it goes. There is a lot to read on here and else where on poly, I hope you take the time to educate yourself. It seems you have already started by being here