Zander and Billy McKnight, summer 2011
Courtesy Billy McKnight
12/10/2011 at 10:15 AM EST
The father of
Mindy McCready's 5-year-old son says he was "disappointed" when the country star fled Florida
, but admits he wasn't surprised by her actions
"I don't put things past Mindy," Billy McKnight tells PEOPLE. "Since I've known her, she often does things that I can't explain."
McCready, 36, is accused of taking 5-year-old Zander away from her mother, Gayle Inge, who has guardianship of the boy. McCready claims
that her son was abused at Inge's home, a charge her mother denies.
Although he was concerned for Zander's physical safety, McKnight says he worries about the boy's mental health.
"He was hiding in a closet
with his mother, with her telling him to be quiet," McKnight says. "Then people come to the closet door and take him away from her. That's a nightmare. No child should go through that."
McKnight, the founder of the country group founder Soul Circus Cowboys, has faced his own personal demons. He has battled substance abuse, and was arrested and charged with attempted murder
in 2005 after a violent altercation with McCready.
McKnight, 45, says that's all behind him
, and that he has been sober for three years.
"I have gotten myself together," he explains. "I'm not a monster. I know people have said things about me, but I am not crazy; Mindy's not crazy. We're two normal people who are just a little left of center."
Custody issues surrounding Zander remain up in the air. McKnight has unsupervised visitation rights for four days a week. Before McCready – who says she's pregnant with twins
– left Florida, she had supervised visitation.
"Every child deserves a mother," notes McKnight, who hopes to have full custody early next year. "Mindy loves him and he loves her. I would never want to take that away from either of them. But she needs to be well; she needs to have a healthy relationship with him."