What is the statute of limitations in divorce?

divorced since 99, then remarried , both of us - now my x is contacting me. curious. details? married over 15 years, no kids. had a house, he invested in apt.buildings, both of us worked - before i signed divorce papers...he told me that he would not sign the papers if i didn't give the house to him and deplete my IRA....I gave him the house , before I even knew what an MSA was....on top of that in the divorce papers...he kept telling me that I owed him money...I left 2x and I remember him flashing bank records in my face saying I owed him rent....I paid him monthly? utterly confused and intimidated...didn't have a concept that he was extorting me...I depleted an IRA to shut him up (18k...) that I ended up paying tax penalty on....after the divorce I inherited a little $...out of the blue he wrote I am wondering what is he up to...how can I protect myself from this predator...?