It doesn't need to be all or nothing, a "discussion" about it kind of puts it in that context.
Do not talk to her about it, just do it. You don't need to explain what you are doing and why, in fact doing so is BAD. Let her ask if she wants to know, and keep your response general, something to the effect of "Just keeping my life fun".
It's ok, beneficial even, if she thinks she may be losing you. Please DO NOT discuss this with her before just making changes for you.
Wanna know how to start, text a friend or two right now, tell them you want to do something new, fun, exciting, whatever and make plans with them to do it. Then when the day/time comes, just tell your W that your going out with "friend(s)" to do X.
M - 9 1/2 years 5/5/16 - Bomb drop - 3 week EA 10/31/16 - We sold house 01/10/18 - D Finalized