The actor had been a part of 10-year-old Evan's life since the pair began dating in 2005, when the boy was just a toddler, but Jenny says he's made no effort to contact his former "stepson" since their split last year.
"I've tried to ask [Jim] numerous times [to see Evan], because my son still asks," Jenny told Howard Stern in a radio interview.
The TV host says that although she no longer speaks to Jim, she has gone through various "channels" to urge him to maintain a relationship with her son. But Jim hasn't responded.
"I tell [Evan] that someday you'll cross paths, meet again," Jenny said. "It's hard. He's been in therapy. It's a process, he's working on it."
Jenny recently began dating NFL player Brian Urlacher. Meanwhile Jim has moved on with Russian model Anastasia Vitkina, who is 20 years his junior.