I seem to recall hearing that a heter of 100 Rabbonim may allow the baal to marry again,have you? (sources please)
The Issur for a man to marry twice is only from Cherem d'Rabenu Gershom. See Rema Even ha'Ezer (1:21) that there are those authorities who are of the opinion that where the first wife was Nishtateit the Cherem does not apply. However the commentaries bring that is accepted practice only to allow a second wife with 100 Rabanim.
Dov Zupnik