I'm going to try to be a middle man for my ex and my friend
With your ex? Why do you want to be a middle man?
I want to start their relationship because both of them are in love with each other
You should stay out of your ex's life. It's not your business about what they do with their life.
I want them to get together as I feel they're both unhappy without each other.
You are a great friend for trying to be a wingman, but don't you think your ex should just stay an ex? It might bring back some unwanted feelings if you try to bring them together. How about just cheering on your friend from the sidelines, instead of directly getting involved?