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 ‘alayhi wa sallam, is His slave and Messenger.
First of all, it should be mentioned that a wife has the right of asking for divorce if she is harmed by staying with her husband. Similarly, the husband is not permitted to keep his wife in marital bond and refuse to divorce her as a way of harming her.
If the said committee acts as the Muslim judge and ruled that this woman is divorced from her husband, then she becomes divorced from him. In this case, she is not permitted to stay with him or allow him to have sexual intercourse with her. The woman should take the matter to an authority that may oblige the man to adhere to this rule and protect her from his evil.
As regards her marrying the second husband, if this happened after her waiting period expired and with the consent of her guardian and in the presence of two witnesses, then this marriage is valid.
However, if the committee [the Fatwa board, as you mentioned in your question] is only specialized in issuing Fataawa and does not have any authority of legislating, then its Fatwa is not enough to invalidate the marriage. In which case, she is still considered as his wife i.e. the first man) and she is not permitted to marry another man unless he divorces her or the judge divorces her from him, or any authority [or person] who is authorised to act as the judge and then her waiting period expires after her husband divorces her or after she is divorced by the judge.
Allaah Knows best.