I'm a BW and would recommend great caution with the use-counseling-as-an-entre approach. You don't have "issues" to confront; you have your infidelity and your years of dishonesty about it to confront, first and foremost. Entering counseling for other reasons is manipulative and will likely result in your wife losing faith in MC altogether-something that might be really detrimental to your healing.
Far better, IMO, to start with honesty, rather than with a ruse. If you want to confess in the presence of a counselor, then be up front about the need for a mediator for a discussion you've been postponing.
Personally, I'd recommend having an MC appointment set for after confession. (For that, I'd do a complete timeline--with details.) I would have been mortified to have confession in another's presence. The emotional response--even if infidelity is suspected-- is enormous, and I simply would be unable to stay in the room with a counselor after disclosure.
It would feel both like an invasion of my privacy and extremely manipulative--as though it was planned specifically to inhibit my response. (And isn't it, really?)
There's no way to do this easily. Trust me--I learned of the earliest infidelities a dozen years after the fact. My husband angled for the MC approach, and later admitted he planned to "tackle other issues" first. Had he been honest with himself, he'd concede the "other issues" were largely the result of the disconnect his lies had created and his need to find fault to justify his cheating and subsequent cover-up.
As it was, I was willing to R. Had he put me through *any* period of MC before confessing, I would not have been. That level of attempting to manipulate outcome would have ended it right then and there.
If you do use the MC approach, plan to confess immediately. Don't have sessions devoted to other "issues." They are either manufactured or need to be backburnered because a confession is going to result in a complete change of focus that will dominate for at least 2-5 years (and plan on the slow track, given the long-term deception).
I'm sorry you find yourself here, but given the circumstances you couldn't have found a better place. Good luck to you-- truly, I wish the best for you.
[This message edited by solus sto at 8:31 PM, March 14th (Friday)]