Despite the apparent similarities, cheating and swinging are completely different things.
Cheating is the worst foundation for a swinging lifestyle.
It sounds to me as though you two have lost touch with each other.
Talk to her about this sad situation.
If she seems amenable, then confess your own peccadillos, but it sounds as though you may be headed for a breakup.
i think you and i should fuck
why tell...look you both are cheaters and it seems that you can do it and still stay sane and in your relationship sooooo...why fuck with telling her, and confessing and getting your life all messed up. What you did not know did not hurt you? Well, the same for her. Just enjoy yourself and be safe.