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, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
First of all, we draw your attention to the fact that fatwas regarding such statements and whether divorce counts with them or not should be referred to trusted local scholars in your country because they are more knowledgeable of the customs and practices of the people there.
What is apparent - and Allah Knows best - is that the statement "I you divorce give" is the same as "I divorce you"; they are both in the present tense, which is not an explicit format of divorce, so divorce does not count with this format except if the husband's intention was to divorce. However, scholars explained that if the common practice of a community is to use this format to divorce or to intend an immediate divorce, then it is considered an explicit format of divorce and divorce counts without the husband's intention. The Hanafi scholar Ibn Nujaym said, "Divorce does not count in the present tense unless it is the common practice to use it to issue an immediate divorce, as is stated in Fat-h Al-Qadeer ... If the wife said to her husband, 'Divorce me,' and he responded, 'I divorce you,' (in the present tense), then divorce takes effect according to the scholars of Samarqand." For more benefit, please refer to fatwa 269398.
As for saying 'div' or the like without saying the word 'divorce' in full, the basic principle is that divorce does not count with it because it is not explicit; however, if it is common in a country that it is pronounced incompletely in this way, then this does not prevent divorce from taking effect. The common practice of the people is what is taken into consideration in this respect. Al-Qaraafi while addressing divorce with the words 'Taaliq' and 'Muntaliqah', wrote, "If there comes a time when the word 'muntaliqah' is commonly used to issue a divorce and the word 'taaliq' is no longer used to initiate divorce except rarely, then the word 'taaliq' does not make divorce count except with the intention (of the husband) while if he says 'muntaliqah', it counts as a divorce, contrary to the current situation in our present time." [Al-Furooq] So he made the word 'muntaliqah' count as a divorce in accordance with the common practice of the people although it is not a word of divorce in principle. For the same reason, he said that the word 'taaliq' does not count as a divorce although it is an explicit word of divorce in principle.
As for the format 'I divorce', it does not count as a divorce because it is not addressed to the woman (it does not include the pronoun 'you'). So saying "I div" does not count as a divorce with greater reason. Therefore, what this Mufti scholar said is correct.
Allah knows best.