TheOtherDave hits on some great points. I don't have much to add except to say I don't see so much a distinction between 'breaking' a promise and 'repudiating' one. In both cases, you break the promise. When you 'repudiate' you have good reasons.

I cannot stress enough the importance of TheOtherDave's point 1. The conditions of your relationship are different. Whether the marriage succeeds or fails will depend on what sort of new agreements you are able to reach.

If you haven't already done so, it might be a good idea to sit down with your wife and write down all the areas of contention so you are clear what they are. If you're seeing a therapist, you can do this in your regular session. Hold off on proposing solutions. Just get them all down. (But not every area of contention, just those that can be traced back to your change of worldview.) Then take them one at a time.

While you're doing all this, keep in mind, you have an unfair advantage. You can remember what it was like to be a Christian. She can't remember what it's like to be an atheist.