Think of it this way, if you were contracted to build a house but never told the person you weren't really a carpenter. You work very hard on the house. You have poured the foundation and put up the frame. Then your employer finds out you really aren't qualified to do what you are doing (even though you are doind your best) and breaks the contract. Does that foundation or frame disappear? No. Neither does your past marriage. It is just null because you ex forgot to let you know he was crazy before you married him.
I am not referring to S in the sentence about the crazy ex. I am referring to my friend's crazy ex.