McCready, who had a No. 1 hit in 1996, "Guys Do It All the Time," sued last month in Davidson County Circuit Court, the Tennessean newspaper reported. The lawsuit claims the alleged assault hindered the country singer's ability to book performances and other work.
William McKnight was charged with attempted murder after he allegedly broke into the 30-year-old singer's home and beat her severely in May 2005.
"One of the problems is that, literally, venues worried about whether ... McKnight would show up and someone would get hurt," spokesman Paul Berg said. "It's been very interesting to see how difficult it's been to even put her someplace to do a free show to raise money."
McKnight's attorney, John Norris, said McKnight was disappointed by the lawsuit.
"Based on the circumstances of this relationship, it's hard to understand where she came up with that figure," he said.
Berg said the $3 million was derived from both lost potential income and the emotional trauma she endured.
McCready's legal problems began before the alleged attack.
In 2004, she pleaded guilty to fraudulently obtaining OxyContin at a Brentwood pharmacy. She was also arrested and charged with drunken driving and still faces that charge and another for violating probation.
Last July, McCready learned she was wanted in Arizona for her involvement with an alleged con man, but the charges were dropped in November.
McCready is raising her 2-month-old son, Zander, by McKnight.