A number of things can shake up a person's life, but divorce is definitely one of the biggest. Whether you initiated it or not, dealing with the aftermath takes a great deal of emotional fortitude.
Most people start to identify themselves in conjunction with their spouse, especially after several years of marriage. Having that identity wrested away in a divorce is a soul-shaking and world-shattering event. There is no more "family" the way you previously defined it, and it's something that affects both you and your children.