Snooping is wrong. If it weren't, we wouldn't hide it when we did it, would we? We know it's wrong, but we do it anyway. I did it too, so I understand. Snooping makes us feel awful too, no matter what we find out. I know I never felt better afterwards, only worse. It's an unhealthy compulsion.
As the vets and MWD will tell you, snooping is a form of pursuit. It also openly displays a lack of trust to your W (put aside whether that lack of trust is justified).
I guess I'm with Tread - apologize if you're sorry. But I wouldn't bother pointing any fingers at her or trying to justify your behavior. It'll cheapen your apology. If you really intend not to do it any more (and plan on totally sticking to that) then tell her it made you feel horrible and won't do it any more.
Think of it in terms of, you've done something wrong, so how do you make amends for that? Forget this is your W or this may hurt your cause. The apology is for you, not her.
Me-47,XW-43 S13,S16 M:18 BD:4-23-17 W filed:7-17-17 (5 months of in-house separation hell) W moved out:1-6-18 D granted:2-15-18 Decree signed:3-29-18