Seriously, try to figure out who the most dangerous litigators the estranged might try to consult, and check them out for a consultation. You might actually hire one of them, but the point is-- conflict the badazzes from consulting with or representing the estranged. You need to move fast before the estranged does the same thing.
Can get pretty expensive, but worth it if you can afford it AND if serious property division and/or children disputes are possible.
This strategy can sometimes get extreme enough to require consultations state-wide.
If you consult someone like "Froglaw's" old partner and like them enough to retain them, ask that lawyer before setting forth on a conflict-generating tour of the matrimonial bar.