We all grieve on our own terms and our own time. Initially I think what gets us the most is the rejection and the shock of the split. It usually hits us all pretty hard. I am not sure the circumstances of your relationship, but maybe you had your chance to accept the fact that this relationship is over and now you may realize that it could be for the best. It may have just happened that you received your good news during the same time you were coming to this realization. It probably also lifted your spirits and help you to realize that things will be okay. If you accept that the relationship is over, you are also going to accept that your wife will most likely find someone else just as you will most likely find someone else as well. Sometimes when we split it is actually for the best. It does not mean that we no longer care about the person, but maybe things just are not able to be worked out and best for both people.