Thanks for sharing and welcome to the forum !!
Take a few deep breaths. Your wife is the one who brought it up after spending a lot of time with your friend. Just relax. You may not have to do anything. Let them develop their relationship and see what happens.
Read a lot on this forum.....you'll learn a lot.
I find that it's better not to try to "move things along" or try to control things. Human connections take on a life of their own. Create time for the three of you to spend time together as well as time with her and time they can spend together. Considering the distance, etc... it might take a while.
That's good....you won't be able to try to rush things