Will a pre-nuptial protect me and my small income and bank account from her endless trips to court?

Fiancee is in arrears due to prolonged illness during which he could not work. Current on his payments slowly paying down arrears. Ex-wife is a vicious alienator (wish that were an exaggeration but it isn't) We want to get married, wanting to protect me from the ex-wife who grossly abuses the system and relies heavily on fiancees inability to afford the process of going after her for harrassment and contempt of court ordered visitation etc. She uses the family court heavily, we have to fight things she brings, like endless petitions to increase support etc every few months. I have no assets, I rent a home dont own one, have no savings or property, dont even own my car I'm making payments and I am disabled, he helps me get to physical therapy and looks after me when I'm ill, which is sadly frequent as I have an inoperable (but benign!) brain tumor. We very much want to be married, beyond the emotional reasons it would help him with access to me when I go into the hospital etc. He had 3 children with his former wife who ran away with the children one night while he was at work to be with her high school boyfriend. The youngest is 13.