Praise be to Allah.
We are very upset to hear about this incident in which you have been deceived and lied to, or have fallen victim to the ignorance of this evil man. The final ruling with regard to mutah marriage is that it is forbidden according to Islamic shareeah. This prohibition is the final ruling of the Prophet (peace and blessings of Allaah be upon him) with regard to this matter.
Imaam Muslim said in his Saheeh:
Baab Nikaah al-Mutah wa bayaan annahu ubeeha thumma nusikha thumma ubeeha thumma nusikha wastaqarra tahreemuhu ilaa Yawn il-Qiyaamah (Chapter on Mutah marriage and the statement that it was permitted, then abrogated, then permitted, then abrogated, and this prohibition remains in effect until the Day of Resurrection).
From Iyaas ibn Salamah from his father, who said: The Messenger of Allaah (peace and blessings of Allaah be upon him) gave sanction for contracting temporary marriage (mutah) for three nights in the year of Awtaas [after the Battle of Humayn in 8 AH], then he forbade it. (2499)
From al-Rabee ibn Sabrah from his father: on the day of the Conquest (of Makkah) the Messenger of Allaah (peace and blessings of Allaah be upon him) forbade temporary marriage (mutah) with women. (Saheeh Muslim, 2506)
And also from him (may Allaah be pleased with him): that the Messenger of Allaah (peace and blessings of Allaah be upon him) forbade mutah and said: It is forbidden from this day of yours until the Day of Resurrection, and whoever has given anything [as a dowry] should not take it back. (Saheeh Muslim, 2509).
From Ali ibn Abi Taalib: that the Prophet (peace and blessings of Allaah be upon him) forbade temporary marriage to women and the flesh of donkeys at the time of Khaybar. This was narrated by al-Tirmidhi, who said: the hadeeth of Ali is hasan saheeh and this is what was followed by the scholars among the companions of the Prophet (peace and blessings of Allaah be upon him) and others this is also the view of al-Thawri, Ibn al-Mubaarak, al-Shaafai, Ahmad and Ishaaq. Sunan al-Tirmidhi, 1040.
Either this man who has deceived you is an evil Raafidi who is following the religion of his community, who permit mutah marriages which are forbidden in Islam, or he is a corrupt Muslim who is taking advantage of the matter to fulfil his own desires, or he is ignorant and needs to be educated and advised.
We thank you for sending this question to us and we would like to take this opportunity to invite you to Islam, the religion of truth, which came to protect peoples life, honour and wealth. You will find information on embracing Islam in the first sections on our web-page. We pray to Allaah to help you to do that which is good and to protect you from evil things and evil people. May Allaah bless the Chosen Prophet.