I think I need an affair to save my marriage

Married 12 years, wonderful wife and mother with one major exception: an absolute fish in the bedroom. No desire whatsoever. We've done counseling and tried therapies, and obviously have talked it out and fought it out: nothing changes.

It wasn't always like this. In our early years she was all over me. We have since had kids and developed hella more responsibilities so some slowdown is not unexpected. But her major excuse for her complete disinterest is that we don't do the same things as when it was just us, so she doesn't feel the same feels. No shite, woman! That hasn't dampened my desire! And the wonderful mother you've evolved into only adds to my fire. But I guess its the opposite for her. She apparently wants to have me around as husband and father and provider, but frick my 24 year old self.

I know the honorable thing would be to divorce but I refuse to do that to the kids. This is an itch that is not getting scratched and it has become so intolerable it is causing resentment that is bleeding into other areas. My family deserves better. I have to scratch this itch without them knowing.

An opportunity has presented itself. A couple I know just divorced. The wife made a pass at me a few years ago. At the time I played dumb. But since then rumors have swirled that she is a freak and they were members of the pineapple gang (makes sense looking back). Now she says she is job hunting in another city so she won't be around long. I think if I am clear upfront that this will just be a sex transaction that it won't deter her from leaving and I will be in the clear, itch scratched and I can release the resentment so harbored and be a better member of my family.

I am still on the fence here and could really use some poignant thoughts to help me decide what to do. If you've pulled off a successful affair I would really like to hear your story and advice.