I have developed a great natural friendship with a property manager over the last 5 years or so. 

Everyone's motivation is different.Learn, study, attempt, take risks and when the opportunity arises - give back with no expectations and life will greatly reward you with money and great friendships!

While money is obviously made through such friendship, that is just a by product and not the main motive ;)I am finding success does not occur without criticism.

In this spirit I now have developed numerous friendships, looked at some deals with others, and helped them in there journey.

Maybe you can develop a long term friendship with him.

Quality of friendship (nor closeness of relationship) is not indicative of integrity and likelihood of getting paid back.

As far as your friend knowing what you sold it for...you'd need to do a double closing, which that in itself isn't as easy as it used to be..but your friend could certainly find out on the county records what you sold it for..Your friend is going to ask you anyway...so if this is a true friend, I'd be more concerned about the friendship then the $$.

He’s a friend and I’m not sure if a contract would be the best approach due to our friendship.

From my perspective, anything more is based on the value of buying out your interest and not necessarily based on the value of the website you developed and control.I think its more important to focus on making sure your friendship is fully intact when your done.

I look forward to growing my friendships, knowledge and investment portfolio.