I ask this having seen a few posts about being asked, and still lying.
As mentioned I have been put in this position twice in the past 18 months, and both times I have answered every question truthfully. The first time I clearly didn't say enough, as my wife seemed to think it was a phase I was going through, and that it's not really a constant part of me. The second time I was sure to clear that up.
I think there are four categories here:
1) She asked, I lied, she found out later anyway.
2) She asked, I was honest about it.
3) She hasn't asked, but I would lie.
4) She hasn't asked, and I would be honest.
Which category are you?