Why did the Catholic Church change so radically after Vatican II in regards to the status of Jews? Before Vatican II in the 1960s, the Church was overtly anti-Jewish. For example:


St. Thomas Aquinas writes in De Regimine Judaeorum (also called Epistola ad ducissam Brabantiae) that "the Jews by reason of their fault are sentenced to perpetual servitude".
The Church had the Good Friday prayer that addressed "the perfidious Jews." That prayer is no longer said by most Catholics.
The Church sanctioned the expelling of Jews from many nations.
The Church in some places made the Jews wear special symbols so that they could be distinguished from gentiles.
In the 17-19th centuries you had a series of popes (e.g., Pope Leo XIII in his encyclical Humanum Genus) condemning the rising influence of "Judeo-Masonry."
Pope St. Pius X had a conversation with Zionist founder Theodore Herzl and told him that he can't recognize the proposed state of Israel until the Jews recognize the Church and convert.
etc.


This overtly anti-Jewish attitude of the Church that existed for 1960-odd years just seemed to vanish after Vatican II, and was replaced with a positive view of the Jews. I've even heard senior Churchman refer to Talmudic Jews as elder brothers of Catholics. This about-face on the subject of Jews is just one of many radical changes that occurred to the Church in the wake of Vatican II.

If the full deposit of the faith was revealed by Jesus, then how can the Church teach contradiction? How can the Church teach one thing about the Jews for nearly two millenia, and now practically fawn over them?
I disagree with the OP about his thesis that the Church has always been overtly anti-Semitic/Jewish.  The examples are not compared to the time period in which they were expressed to see what the rest of the world said and how they said what they said.  As a matter of fact, the Church has not been anti-Jewish in any official capacity.  

St. Augustine has been infamously accused of many things including being anti-Jewish, yet his ruling in favor of a Jewish man in a case brought before him by the Jewish man in which the man's mother sold property that belonged to him to a bishop.  The bishop in question refused the man's request to return his land in which he offered to pay the bishop.  This is why the man brought his case before St. Augustine.  After reviewing the case, Augustine wrote to the bishop in question and told him he was sure he wished to do the right thing and told him he had to return the Jewish man's land to him.  Sounds anti-Jewish?  Didn't think so, because Augustine was not an anti-Semite.  Nor was Aquinas.

Gregory the Great "emptied the papal treasury to ransom prisoners of the Lombards and to care for persecuted Jews and victims of plague and famine" (http://www.catholicculture.org/culture/library/fathers/view.cfm?recnum=3466).

What Vatican II did was to open new frontiers by referring to the Jews as our elder brothers in the faith from which all Catholics come.  Much good fruit has been borne with the improved relations between Catholics and Jews (amongst all religious traditions and non-Christian religions).