I'm uncomfortable with my wife being a surrogate to a short-term friend
Why is your wife becoming a surrogate?
It was a favor he wants to return, I don't like that ... it's me
At the end of the day, it is your wife's body. Not only that, it can help you financially a ton. You should try to get over these feelings as this is a beautiful process.
I'm a jealous momma's boy, what can I do?
You just need to drop the jealously and let her do what she wants. There's nothing wrong with being a surrogate for someone.