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 'alyhi wa sallam, is His slave and Messenger.
The first divorce that you had uttered to your wife is considered as a divorce as long as you intended it and deliberately uttered it. As regards to writing the word divorce, then the most preponderant opinion is that it does not take effect unless it is accompanied by intention. Now, what has to be looked at is the term used for divorce that you wrote in the letter.
The term for divorce that you wrote could be one of two things:
1 - It could be that you wrote the term, “You are divorced” meaning that it is two divorces. If this is the case then it is considered as two divorces and thus you cannot take your wife back unless she marries another man who then divorces her. However, Imaams Ibn Taymiyyah and Ibn Al-Qayyim consider this as one divorce.
2 - It could be that you wrote, “You are divorced, you are divorced.” If by the second expression you meant to emphasize the first, then it is considered as one divorce. In this case it will be considered as the second divorce (along with the first one), so you can take her back as long as she is still in the waiting period. If her waiting period has expired, then it is not permissible for you to take her back except with a new dowry and a new marriage contract. So, if you want to make another divorce, then you already have two divorces and with the last one it will be the third and final one. Nonetheless, Imaams Ibn Taymiyyah and Ibn Al-Qayyim consider that the term, “You are divorced, you are divorced,” as one divorce, and with the last one it will be the second divorce.
3 - It could be that you wrote it as follows, “You are divorced and you are divorced.” Ibn Qudaamah said, “If he says, 'You are divorced, and you are divorced and you are divorced,’ and says that he meant to emphasize the first one, it will not be accepted from him because he expressed the first term differently from the second term as the conjunction ‘and’ suggests an addition (as mentioned before) or something different, and this, of course, does not mean an emphasis.” So, in this case it is considered as two divorces, and in addition to the first one, it is three divorces. So this is an irrevocable divorce (and you cannot marry her again unless she marries another man who then divorces her too).)
Finally, we draw your attention to the following matters:
A- One should avoid anything that may cause disputes between the two spouses, and not hasten to utter the word divorce and then regret it.
B- When the husband utters the word divorce it takes effect whether or not the wife knows it.
C- To take the case to an Islamic court in such issues as it is more appropriate for the court to look into these matters, and if there is no such court, then to the Muslim community. There is a great difference of opinion among the scholars on the matters that we have mentioned, and the decision of the judge removes any differences in matters of Ijtihaad (issues on which there is no text in the Quran, or the Sunnah, or the consensus of scholars).)
Allaah Knows best.