if you were sitting infront of me on a table... here are the two things that I would do.
1. Bitch slap you across the face for trying to fuck another while you are married
2. Then right after give a high five and say... good on ya bro.. congrats on the new pussy !

Anyways... regardless of how you word it.. theres no fricking way that you are only interested in her well being... may be atleast for now you can lie to your self., but we all know where this gonna end up.
HERE's my suggestion.
Tell your wife the story ... then get her to talk to that friend of yours and let her handle the things from there on wards... i am sure your "friend" would be more inclined to receive money from your wife than you.
i mean.. if your intentions are PURE as you say they are... your wife would have no problem in understanding it ... your wife aint a retarded isnt it?