For the state of WA what were the laws for prenuptials signed in 1996.

We lived together for four years before marriage. After 13 years of marriage, we have 3 children and I've been the stay at home mom. I want to know if the prenuptial will stand up in court. I signed a prenuptial 7 days before marriage. My husband sprung this on me at the last minute and demanded I sign just two days before leaving for our Hawaii wedding.