Divorce is difficult for children. Young children do not really understand why mommy and daddy are not living together. Older children may not really understand, and they can get the wrong idea as to why their parents are divorcing. But it is not really the divorce that is difficult. The legal separation of two lives is unintelligible for most children, but they don't really need to understand that.
It is the failure of their parent's relationship and the fear or guilt that develops that suggests to them that it is their fault. Which is why during your divorce with children, you want to have the professionals deal with the technical aspects, both legal and financial, to ensure that those matters are appropriately dealt with, while you work on the emotional side of the equation.