It does not have to last, know that going into it. No matter how bad you feel now, or in the future, it will go away with time. Think about it. The build up from meeting your ex to your marriage (or steady relationship for those who didn't marry) did not happen overnight. It built, slowly raised to what it was when you got serious. In the same vein of thought, your marriage did not fall apart all at o­nce either. It eroded over time (sometimes o­nly for o­ne party) until you found yourself where you are today. Even a bad marriage that you're glad to get out of will bring grief, loss, and a flurry of unexpected emotions.