Is my estranged husband entitled to any of my inheritance not yet distributed?

Mostly that's going to depend on where you live and if he survives you. In many states its considered separate. But should something happen to you and your still married then he would possibly be entitled to it. Do you have children ? What you might do is contact a lawyer in your area and write up a will leaving it to whomever. Also they could tell you what some of the state laws are for your area.