The good Bill de Blasio is being threatened by the bad Bill de Blasio

I’m torn about our mayor, who’s torn himself. There’s Bill de Blasio, the man of principle, who uses his power and bully pulpit to get our city do more for, and do better by, New Yorkers left behind — the ones who feel pushed aside, priced out and penned in by policing intended not for their own protection but to protect the rest of us from them. Who’s done that without breaking the city’s bank or its back.

Then there’s Bill de Blasio, the man of convenience, who uses the city’s money to pay off his friends and its officials to drive his personal machine. Who flatly denies his sins when he thinks he can get away with it, and insists his vices are virtues when he can’t deny them altogether.

As he gears up for next year’s reelection bid, it’s all too hard to tell where the good de Blasio begins and the bad one ends. The candidate who got himself cuffed on camera to protest hospital closures is the mayor being investigated for his role in the sale of one of those same hospitals to a developer with a lobbyist who “volunteered” on his campaign.

“This isn’t Watergate,” the mayor usually prone to over-hype, not under-play, his own “historic” doings said last week about another investigation, this one into the despicable deal his administration signed off on to let another developer with another lobbyist who’s tight with de Blasio flip a nursing home for AIDS patients into luxury condos.

Maybe it’s Bridgegate, then, what with de Blasio’s absurd insistence that, despite his reputation for micro-management, he would have said “no” if only he’d been told about this ugly arrangement. (He says the developers lied to the city about the deal, and that he doesn’t remember seeing an email to him that told him about it.)

We only know that top deputy Tony Shorris knew all about it because the city’s own Department of Investigation — led by the treasurer of de Blasio’s 2013 campaign, itself the subject of criminal investigations — publicly shamed and then threated to sue the city’s own top lawyer after he hid and redacted damning documents he bizarrely claimed were irrelevant.

That wild fight within his administration, de Blasio says, is just ordinary government in action.

If the mayor really thinks that, he’s a fool. If not, he thinks we’re fools.

Speaking of keeping secrets, de Blasio promised back in May that “in the coming weeks” he’d deliver a list of all the donors who didn’t get what they wanted, of the bribes he didn’t pay off.

He’s yet to deliver it. Meantime we know more and more about those who did get what they sought. The guy who’d been trying for years to sell the city on his supposedly rat-proof trash bags before he gave big to de Blasio and promptly got his foot in the vault’s door. The real-estate developers who ponied up and saw the mayor catch the animal-rights spirit. The cab-medallion owners whose contributions helped focus de Blasio on Uber’s supposedly awful impact on traffic congestion, which turned out to be not bad at all.

The guys who dressed up as “elves” to personally deliver bribes to top cops who also ended up on de Blasio’s inaugural committee.

Add to the spoiling stew his absurd claim that some of the people who lobby City Hall during the day are “agents of the city” by night, making their conversations with the mayor none of the public’s business.

We now know of six — or seven, if the U.S. Attorney's probe of the Long Island College Hospital closure counts as a separate one — federal, state and city investigations of de Blasio’s administration and political operations.

If he’s right that there’s no fire to go with all this smoke, that really would be historic.

And when he cries that this is all a conspiracy by billionaires, remember that these probes are led by a U.S. attorney appointed by a Democratic President; appointees of a Democratic governor; the Democratic city controller; a Democratic district attorney, and the Democrat who runs de Blasio’s own investigations department.

One not-exactly-saving grace: In contrast to Gov. Cuomo, who has two former top aides being probed for cashing in on their public service, de Blasio has run an administration in which no official has been accused of personally pocketing money. It’s all about using New York’s fisc to advance his agenda and personal power and prestige.

De Blasio’s implicit argument — that because he’s on the side of the angels, his shady deals don’t stink — stinks.

If this guy’s four or eight years in office end up as another cautionary tale like the one term of his old boss David Dinkins, sandwiched between decades of more conservative and successful mayors, be Blasio will have himself to blame for bringing down his progressive agenda.

With so much smoke, can there be no fire?