Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Written divorce without uttering the words of divorce or reading what is written is valid only if the divorce is intended since writing is considered among the illusive expressions that might be understood in more than one way.
If one writes that his wife is divorced thrice whether it is considered as divorced thrice or not, the four schools of thoughts are of the opinion that it is a divorce three times.
Sheikh al-Islam Ibn Taymiyah is of the opinion that it is considered only one divorce.
We would like to say that the matter of divorce is critical, hence we advise you to consult an Islamic court or an Islamic Centre.
Allah knows best.