All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
We will mention some points for benefit, but we advise you to consult with a scholar orally or refer the case to an Islamic center directly so that they would ask for required details and give you their fatwa based on the information which they hear from you. For benefit, we say the following:
First, when the man orally gives a divorce using explicit words of divorce, it takes effect whether he held the intention of divorcing or not. Ibn Qudaamah wrote, "Explicit divorce does not need an intention; rather, it takes effect even if the husband does not hold the intention of issuing a divorce, and there is no difference of opinion among scholars in this regard." [Al-Mughni]
Second, a written divorce is a metaphor of divorce; divorce does not take place with a written divorce without the husband's intention, which is the determining factor in this case. The Shaafi‘i book Al-Minhaaj reads, "If the husband writes down the words of divorce and does not hold the intention of issuing a divorce, it does not take effect and falls under the category of idle talk."
Third, if the husband lies about divorcing his wife, divorce does not take effect according to the most likely correct view. The Shaafi‘i book Asna Al-Mataalib reads, "If the husband lied about divorcing his wife, divorce does not take effect."
Fourth, divorce issued under moral pressure does take place. The pressure in such a situation does not affect the validity of the divorce unless it reaches the level of duress. The criterion of determining duress is that the person threatening the husband should be able to carry out his threat and the husband believes that he would most likely carry it out if he does not comply with his request. Moreover, the compulsion should be as severe as the threat of killing, painful beating, long imprisonment, deprivation of all one's wealth or a great part of it, and so on. Duress includes threatening the person himself (the husband in this case) or someone regarding whom he would be harmed much if they were harmed, like his wife and relatives.
Fifth, Allah, the Exalted, allowed polygamy for the man who is able to maintain justice among his wives. So if the man marries a second wife, his parents have no right to command him to divorce her for no valid reason. The same goes for his first wife. It is impermissible for her to take the children and travel without her husband's permission in order to pressure him and force him into divorcing his other wife. Abu Hurayrah reported that the Prophet, sallallaahu ‘alayhi wa sallam, forbade the woman to demand her sister’s divorce so that she would deprive her of the blessings that she has. [Al-Bukhaari]
Lastly, we would like to emphasize the need to consult verbally with a scholar or refer the case to the Islamic center in your country.
Allah knows best.