All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.
The ruling in this case is as those muftis told you, and we have previously underlined it in fatwa 92685. It is impermissible for the woman to get married to another man because her husband claims that their marriage is still intact. The Hanbali scholar Al-Buhooti wrote, "(In case of an unverified divorce) The wife cannot marry another man unless her divorce from her husband is verified so that she would not be married to two men at the same time, i.e. one of them is her husband in reality while the other is her husband in front of people." [Kashshaaf Al-Qinaaʻ]
This does not mean that the wife should endure such harm; rather, she may refer her case to the concerned authority addressing marital disputes such as Islamic centers or the like, so that they would relieve her from this harm either by retaining the marriage bond with kindness or by graciously ending it.
Allaah knows best.