Is a prenuptial agreement the best approach?

I have 3 real estate properties (in my name) and other financial assets and am about to be married to a divorced man with 2 children from a previous marriage. We both want to keep my assets separate from his and protect our joint assets and my assets from his ex-wife. He signed an extremely one-sided divorce settlement which has put him in financial hardship (and debt). He supports his children financially but she is constantly coming to him for more money and she seems to now think I'm a new deep pocket for her and her kids. What can I do? - Is this your question? Add additional information