Hide it from her

You decide you're not comfortable with the idea of swinging. A part of you is afraid that if you broach the topic with Ada, she might be interested in it - and even if you ultimately choose not to go ahead with it, you might always be haunted by the knowledge that your wife needs more than you can give her. To spare your own feelings, you decide not to mention it to her.

What she doesn't know won't hurt her, but your actions may have consequences later...