This is a citiaion from "The Chosen Path" - a history of Medieval Jewry by Binyamin Sendler:
R’ Yonah b. Avraham certainly saw it in this light. Following is an extract from the letter that his student R’ Hillel HaChasid (of Verona) wrote to R’ Yitzchok HaRofeh: Letter by R’ Hillel HaChasid
R’ Yonah of Barcelona (originally of Gerona) was the primary instigator of this controversy that brought about all the calamities that befell the Jews in France. At that time R’ Yonah’s heart melted within him, and he vowed to make a pilgrimage to the Rambam’s grave and remain there for seven days, begging forgiveness from the Rambam for slandering his works. He publicly confessed in these words: “I am embarrassed and I regret that I opened my mouth against our holy master R’ Moshe b. Maimon and his works. I say now for all to hear: Moshe is true and his Torah is true and we are all frauds . . .” All the places where the Rambam’s works were derided were then filled with awe and fear, and all who had contested him accepted the verdict of heaven. R’ Yonah set up his yeshiva in Barcelona and every time he taught he would cite the Rambam’s opinion and say, “Thus says R’ Moshe, and so it appears to me.” He never again argued with the Rambam’s conclusions. Nevertheless, he was punished for delaying the fulfillment of his vow for many years until he had almost forgotten it. He left Barcelona with the intention to take a boat to the Rambam’s grave in Eretz Yisroel, but he was detained in Toledo where the Jews begged him to stay for a year or two, so he opened his yeshiva there (and there he died).
There is no authentic source that suggests that R’ Yonah wrote his Sha’arei Teshuva as a penance for the part he played in this controversy.
He adds in FOOTNOTE:
1 This is as reported by R’ Hillel HaChasid. He relates that “not only were the Rambam’s works burned, but the fire to burn them was taken from the flame burning before their altar in the great cathedral in Paris. . . Should you ask how it is known that the burning of the Talmud was divine retribution for the destruction of the Rambam’s works, I would answer you that there was less than forty days between the two burnings, and the Talmud was burnt in the same place as the Moreh was. The ashes of the Moreh were mixed with the ashes of the Talmud.” These details, however, are suspect; the two events did not occur in the same year, and it seems unlikely that the works confiscated in Provence were carted hundreds of miles to Paris to be burned. It is possible that R’ Hillel’s information was defective.