Alexa Ray Joel at The Rainforest Foundation Fund's 'Some Kinda Legacy' benefit party held at the Plaza hotel, New York City, USA - 08.05.08

The singer joined her disgraced stepdad Peter Cook and his former teenage mistress Diana Bianchi on the witness stand during the first day of her mother Christie Brinkley's messy divorce trial.

And her revelations were the day's most shocking.

She told the court Cook allegedly stormed into a family bathroom while she was taking a shower and ordered her to take care of a leak downstairs.

Alexa claimed that she was not given a chance to get dressed, and her stepfather pushed her head into the leaked water and forced her to clean it up while she was naked.

Earlier in the proceedings, Cook had broken down during cross-examination by his own attorney and Bianchi revealed she had been paid to keep quiet about her affair with her former boss.

The trial continues.

Source: WENN