KEEPING the number means you are doing the SAME THING cheating spouses do. If you are divorcebusting, you are in there 100%. You can't be in a marriage, but have some girls number you picked up... It doesn't work.
And I can guarantee you that you won't fight for your marriage half as much while you have that number in your back pocket.
You are turning into your wife dude. And not the pretty part either.