Estate Law Questions? Ask an Estate Lawyer.
I will be happy to assist you. Whether you decide to get married to this man is irrelevant. Married or not married he cannot direct your movements or dictate who you visit whether he is alive or dead, husband or not. Even if you signed such a paper, who would be around to enforce it? It is unenforceable, and no attorney would even draw it up.
Slavery is illegal, there is no form of "legal slavery". You are free to visit your family, now and after he dies, and do not let him tell you otherwise.