TIM DONAGHY isn't bitter. At least, that's what he says.

He knows he screwed up, that he alone is to blame for placing that first bet on an NBA game, which eventually turned into more than 100 bets.

"I have to look into the mirror and realize I was the one that crossed the line and made some terrible choices, and anything that was thrown my way was deserved," he said.

Yet, you also get the sense that Donaghy wishes others feel the same way when they see their own reflection. More than 2 years after he pleaded guilty to gambling and wire-fraud charges, the 42-year-old Havertown native is still pondering what he considers to be the "biggest mystery" of the whole ordeal:

Why did the feds only prosecute him and two childhood friends from Cardinal O'Hara High?

He thinks they missed the big picture - or didn't want to see it - of fraud in the NBA, possibly involving other crooked referees.

"I've talked with FBI agents who were adamant that seven or eight more people should have been indicted, including other referees," Donaghy told the Daily News yesterday.

He says he's not bitter. But do you believe him?

These days, almost every statement he makes is followed by that question.

Since he completed his prison term last month, Donaghy has been trying to repair his relationship with his four daughters - "Letting them know the future is going to be better than the last couple years" - while publicizing his tell-all memoir, "Personal Foul,'' which is as polarizing as Donaghy himself.

In the book, Donaghy claims that he never used his position to impact a basketball game that he gambled on. And he says that while the hardwood on the court might be level, the playing field in the NBA is not, with referees and league executives favoring marquee players and big-market matchups with an eye on the bottom line.

Again, do you believe him?

An ESPN report this week concluded that his betting strategy - which Donaghy says was based largely on his knowledge of referees' biases toward certain players, coaches and owners - wouldn't work most of the time. (Donaghy retorted yesterday that ESPN tried to discredit him to preserve its contracts with the NBA.)

So if Donaghy's methodology didn't work, he had to be fixing games to win at a 75 percent clip, right?

Not necessarily, according to retired FBI special agent Phil Scala and others who reviewed game tapes and found no evidence that Donaghy was making calls to manipulate the score.

This has left basketball fans deeply divided about Donaghy. Not necessarily a bad thing when you're trying to sell books.

Scala, the man who put John Gotti behind bars, said yesterday that Donaghy is telling the truth.

But after reading Donaghy's quote that other referees should have been indicted, Scala responded, "I don't know about that."

"If there were people that should have been indicted, they would have been, including other refs," he said. "We don't play those games."

Asked if the FBI had uncovered evidence of criminal wrongdoing by other NBA refs during the course of the Donaghy investigation, he said, "We did not.''

But Donaghy wants you to believe him. He even took a lie-detector test in 2007 and "passed with flying colors,'' he writes in his book.

Yesterday, he reflected on how he besmirched the family name and disappointed his father, Gerry Donaghy, a former NCAA referee.

"It was strained, but over the process of this whole thing, it's actually grown stronger," he said of his relationship with his father.

He hopes to someday speak at college campuses, to help prevent students from "crossing a line that we just shouldn't cross.''

"I think it's a powerful message I can deliver," he said.

He's still participating in gambling treatment, but, he said, "When you think about the devastation I caused my family, my children, my parents, that's all I need to think back on to keep me away from taking that step to gamble again."

And Donaghy, a product of Drexel Hill's storied basketball community, had a message for his old friends back in Delaware County who might read this:

"I'm truly sorry for what I did. I made some terrible choices," he said. "I wish I could turn back time, but I can't."

He sounds contrite. But do you believe him?