Welcome to the forum WH,
I have been struggling with these issues since I was a kid, and well into my marriage. I joined the forum about 3 years ago. Little by little, I disclosed things to my wife. Since your wife has found out about your problem, it makes things easier. However, it's unwise to go ahead and tell her everything you ever did or thought; she doesn't need to know it and it just does more harm than good.
I once heard the definition of being "powerless" (which is a sign of addiction) as follows: You never know which time will be the one when you lose control. Sometimes we DO seem to be able to control ourselves. But it's those times when we can't that indicate the true extent of our problem.
It sounds like, despite the difficulties, you are pretty much getting along with your wife and able to communicate openly. This is a tremendous blessing.
Regarding all those worries about messing up your life and your relationship with your wife because of all those images in your head--Don't think about that now. Just focus on what you can do, from now on, to make things better.
Did you download the GYE handbook? It is full of tools and attitudes which are very helpful for this struggle. You'll find the handbook (and lots of other ideas for how to get the most out of GYE) at this link:
www.guardyoureyes.com/breakingfree/first-time-here The best thing you can do is just keep on posting; keep in touch.
Good luck to you,
Elyah