The arch rivals faced off in court for the third consecutive day on Thursday as Hadley was grilled about his relationship with his long-time 2GB stablemate.
Hadley was called as a witness in the indecent assault trial of Jones, 85, who has pleaded not guilty to 22 charges related to alleged incidents stemming back to 2003.
The former mornings host agreed he had animosity towards his colleague Jones about the time a radio staffer told Hadley that Jones had indecently assaulted him.
Hadley said he harboured the negative feelings because the breakfast host had been targeting him.
He had been in Jones's sights because he had signed a "secret contract" worth $4 million to usurp the former Wallabies coach in the breakfast slot, he said.
"He was targeting me because he thought I was disloyal," he told a Sydney court.
But the ousting ultimately didn't eventuate as the chairman of Nine - which owns 2GB - pushed for Jones to return, leaving Hadley on as mornings host, albeit his salary doubled.
Hadley said Jones, who won the breakfast slot a record 226 times over several decades, then told colleagues to dig up dirt on him and linked him to a false assault accusation.
When asked about friendly messages he later sent Jones, Hadley said they were common courtesy responses.
"Our relationship was very complicated. We went from being very close to very distant," the broadcaster said.
"He was gracious and I returned it".
He attributed professional success to Jones and said he appreciated what the former teacher did for him.
But Hadley said there had been "stand-up brawls" between the talkback titans during decades of working together.
"We were both under tremendous pressure constantly to deliver," he told the court.
"As a result, it was a tumultuous relationship - sometimes warm and friendly and sometimes hostile."
Jones is accused of indecent assault and sexual touching without consent related to six men between 2003 and 2020.
One complainant is a former radio staffer who alleges he was non-consensually kissed and groped by the longtime breakfast show host over five months.
He tearfully confided years later in Hadley, who later texted the man that "This bloke (Jones) needs to be destroyed".
"It was a reference to (these) proceedings," Hadley told the court.
"I said I'd stick by (the complainant) and I'd support him in every way no matter what course of action he decided to take and that's why I'm here today."
He rejected a suggestion from Jones's barrister, Gabrielle Bashir SC, he hadn't told the truth about the conversation in which he said the radio staffer confided in him.
Hadley previously testified the younger man swore him to secrecy after breaking down in tears and disclosing in graphic terms what Jones had allegedly done to him.
"It would ruin me. It would ruin my career. He's too powerful," the radio staffer allegedly told him after Hadley suggested a police report.
Ms Bashir argued rivalry and concocted allegations were at the heart of the case against Jones.
She suggested Hadley wanted to destroy his rival and had encouraged the radio staffer to make a complaint, which the radio giant rejected.
In texts aired on Wednesday, Hadley vowed to "bury" Jones and used a homophobic slur in profanity-laden texts to the former radio staffer.
The former mornings host maintained "f****t" was not a word he normally used.
In his testimony, the radio staffer denied fabricating the indecent assault claims or coming forward to benefit Hadley.
Jones denies the charges, which are alleged to have occurred during the latter part of his 35-year broadcasting career, when he dominated Sydney's airwaves.
The once-powerful commander of public opinion also broadcast to a national audience for years as a regular commentator on Nine's Today show and a host of a political discussion show on Sky News.
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