OP sorry to say, but it doesn't matter if you think you've been such good friends and so happy without sex, the fact is your husband HASNT! You may have been alright with it, you may have even thought he was also okay with it, but he clearly wasn't and you're extremely naive to believe he ever was. Why would a healthy man with a sex drive be okay with a sexless marriage for 7 years? 
He's either been having it away elsewhere OR he's finally run out of patience and is now at the cross roads. And to honest after 7 years I don't blame him.
You have a decision to make OP. But I have to say, if you wasn't so care free financially and instead you had a huge mortgage hanging over your head still and wasn't so lucky with regards to money, you probably wouldn't have classed the last 7 years as so happy.
It seems like you wish to continue this lovely life style you've been having on YOUR terms ie no sex or intimacy.
If you don't want to be intimate with your own husband let him go to find somebody who will be. Being "best friends" isn't reason enough to stay with him. Is he your best friend because he provides you with this life style? Would he still be your best friend that you wanted to stay with if you were in massive debt? I doubt it...
A marriage involves two people not one. If you aren't willing to be a wife, let him be a husband to somebody else. But to be brutually honest I'm surprised it's taken 7 years for this to happen.
It's not all about money and a nice lifestyle OP. Either sort yourself and your marriage out or be prepared to go through divorce and lose him to somebody who actually wants him as a husband and not just for the money/lifestyle he provides