The story was a bit different at least in the words of Tartaglia. The crowd that gathered in Milan was death threatening Tartaglia, who got away just in time...

Ferrari was a servant to Cardano who liked the young boy and instructed him. After he defeated Tartaglia he became rich enough that was later killed by his own sister and brother-in-law for his money....

To get an idea of what was life at the time one could read a recent English translation of Cardano's autobiography originally written in Latin:

http://www.nybooks.com/books/imprints/classics/the-book-of-my-life/