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 is His slave and Messenger.
The wife in question must wait until her divorce from her husband is finalized. If her husband does not divorce her and she is harmed because of his absence, she should seek the judge’s verdict to remove that source of harm from her.
By getting married in the way that is mentioned, she has committed a serious sin and her marriage is invalid. Ibn Qudaamah said in his book Al-Mughni,
“[In case of] the invalid marriages such as that of a married woman, that of a divorcée who is still in her ‘Iddah (post-divorce waiting period) or the like, if the married couple knows that their marriage is invalid, then they are adulterers. Accordingly, they should be punished by the due corporal punishment prescribed for adultery, and if she gets pregnant from her new husband, his paternity of that child is denied."
The case in question should be referred to the Islamic courts concerned to issue a verdict therein.
Allaah Knows best.