The problem with emotion is that it is by nature an uncontrollable force. Emotional bonding occurs for reasons of group safety and genetic endurance. But the social bonds that reinforce our emotional states are not necessarily productive of good in our particular situation.
How does love fade? How does the attachment we have for another continue through suffering and pain and abuse? When can one expect to be free of the agony of self that is broken love?
In my past I have been in similar situations and though marriage is much the same as any emotional/sexual relationship it does carry its own weight. I have felt this feeling before, but never to this degree. (Though I probably said that at each breakup along the way in my life.)
When we consider another important to us emotionally the growth period of that emotional bond usually takes a long time to grow and strengthen. When the heart is broken we want the emotions to cease immediately yet for all practical purposes there is no off switch to love.