I've had similar experiences. Sometimes it makes me feel guilty, at other times it convinces me that the extramarital sex helps me live with the things that are lacking at home. I love my wife, but there are gaps in what we can provide each other. Our relationship is built on companionship, not being lovers. There are worse things. But the sexual satisfaction is still missing, and sometimes I indluge myself other relationships to fulfill that. I usually screw those relationships up by being too sensitive during down times and saying things that are hurtful. Like everything else, there are constant ups and downs.

Perhaps you need a break from your outside relationship to assess what you most need and how to keep things in balance. Ask for some time off to assess. Your affair is clearly a bad thing from one perspective, but from another it may or may not be a bad thing. If it enables your marriage to work, it may be the outlet you need to keep things in balance. If it just make you feel like a liar, it isn't. Take some time to figure it out, then your path will become clearer.