Will a prenup protect my estate if I die while married?

I live in New York and I’ve been told that a spouse may be able to go against your Will if you die while still married and get more than what you’ve provided for them in the Will. I’m engaged and I have adult children from my prior marriage. I have considerable assets that I acquired before I ever met my fiancé. I want to make sure that if I die while married to her, what my Will says will be honored and my assets will go to my children. Could my fiancé agree to sign a prenup and waive any right to contest my Will or get any of my assets if die?