Marie Yovanovitch, the former U.S. ambassador to Ukraine, testified Friday in the House's second public impeachment hearing.Driving the news: Trump took to Twitter as Yovanovitch testified to attack her diplomatic career, saying that everywhere she served "went bad." House Intelligence Chairman Adam Schiff (D-Calif.) read the tweets directly to Yovanovitch about 20 minutes after Trump posted them.Yovanovitch said that she felt the tweets were "very intimidating."Trump's tweets even led Fox News anchor Bret Baier to call it "a turning point in this hearing."Other highlights:Yovanovitch used her opening statement to push back on a number of unsubstantiated allegations that led to her ouster as ambassador, including that she directed embassy staff to ignore President Trump's orders and that she crafted a "do not prosecute" list for Ukrainian officials.The former ambassador offered a defense of the State Department's work in the current era while criticizing corrupt conduct that "undermines the U.S., exposes our friends, and widens the playing field for autocrats like [Russian] President Putin."She said she felt threatened by the fact that Trump said she would "go through some things" during his July 25 call with Ukrainian President Volodymyr Zelensky.Committee Republicans attempted to defy the agreed-upon rules for the impeachment inquiry at the start of their questioning period — likely an attempt to stage a bad television moment for Schiff.During a line of questioning from Rep. Jim Himes (D-Conn.), Yovanovitch said that if she had been kept on as ambassador she would not have recommended an investigation into a conspiracy theory linked to the 2016 election, a freeze on military aid to Ukraine or an investigation into the Biden family.After being questioned by Rep. Brad Wenstrup (R-Ohio) about the president's ability to fire diplomats at will, a key GOP argument for the former ambassador's ouster, Yovanovitch agreed but asked: "What I do wonder is why was it necessary to smear my reputation also?"The backdrop: During her closed-door deposition before the House impeachment committees, Yovanovitch testified that President Trump's lawyer Rudy Giuliani led the smear campaign that led to her firing.Yovanovitch is a career diplomat who also previously served as the ambassador to Armenia and Kyrgyzstan under the administrations of George W. Bush and Barack Obama.Watch:Yovanovitch defends State Department's workYovanovitch says she felt threatened by mention in Trump-Zelensky callYovanovitch calls Trump's mid-impeachment hearing tweets "very intimidating"House Intel Republicans attempt to defy Schiff despite inquiry rulesRead:Schiff's opening statementYovanovitch's opening statementGo deeper:Read Yovanovitch's closed-door testimonyHighlights from Bill Taylor and George Kent's public testimonyA viewer's guide to the impeachment hearings