Most people are aware of his competition with the lesser connected Borromini. This stemmed from Borromini being the superior architect. Even so, Bernini often won commissions over Borromini due to his connections. It really comes down to who you know.
During the Barberini Papacy Bernini could do no wrong and won any commission he wanted due to the Pope pulling strings or hiring him outright for work for the Church. More on his connections in a different post. This post is about love and murder.
Many people know about the pain of love, the agony of love, the kind of love that drives us all insane. It forces us to do things we wouldn't otherwise dream of doing. This is true even for a genius like Bernini. You can't make this stuff up...the great Bernini was caught up in a love triangle that Shakespeare would envy.
Bernini by his own admission was a man who had "great inclination to pleasure." Bernini was having an affair with Costanza Bonarelli who was married to Matteo Bonarelli, one of Bernini's assistants. Bernini was open about his affair. Some think she was the model of Divine Love for Pope Urban's tomb.
Bernini heard a rumor that his brother Luigi was also having an affair with his Costanza. One day, Bernini lied to his brother stating that he was going to the country. Instead, he went to Constanta’s house to spy on her and to see if his brother would show up. Sure enough he saw his brother leaving Costanza's house, with her kissing him as he left.
Bernini followed his brother to St. Peter's and attacked him with a crowbar. He ruthlessly beat him intent on killing him. It is likely a combination of being humiliated as well as the love he felt for Costanza. Luigi escaped with two broken ribs and a hell of a beating. It doesn't stop here. The next day Bernini ordered his servant to go to Costanza’s house and cut her with a razor. Bernini wanted to insure that she wouldn't appeal to another man. The funny thing is Bernini was mad that she cheated on him, but he was having an affair with a married woman and was shocked when she strayed even further? In her bed Costanza was cut with a razor. Bernini once again attempted to attack his brother with a sword. He escaped into Santa Maria Maggiore.
The Pope intervened and lessened the charges. Bernini was forced to pay a fine. Luigi left Rome and was replaced at St. Peter's as a superintendent on the commission. The Pope absolved Bernini due to his excellence in art.
A bust of Costanza is now in Florence. It is thought that Costanza's likeness was used in Bernini's Medusa at the Capitoline Museum in Rome.