Nearly 50 years after Senator Ted Kennedy left a young woman to die in a shallow pond — and America went on to reward him with a lifelong career in the US Senate — we are finally beginning to reckon with the Kennedy myth.

But only just.

The new film “Chappaquiddick” is, to date, the most brutal and honest account of what happened that night. But it’s also something else: an indictment of our collective hero worship at the altar of Brand Kennedy, which bred so much corrosive entitlement that surviving brother Ted, the family beta male, went home to sleep it off after leaving a loyal young staffer to die alone.

“Chappaquiddick” is a much-needed counterweight to two current hagiographies: CNN’s docuseries “The Kennedys,” airing to high ratings on Sunday nights, and Netflix’s forthcoming documentary “Bobby Kennedy for President.”

JFK and RFK remain, of course, the family lodestars. But in 1969 Ted was next in line, and he had a lot of public sympathy.

His brother Robert had been assassinated while campaigning for president the year before. President John F. Kennedy was assassinated in 1963. Ted himself barely survived a plane crash in 1964, dragged to safety by Senator Birch Bayh (the irony) and hospitalized for five months. It was assumed, within the family and without, that Ted would run for president in 1972. He had three small children and, the July weekend he went partying in Chappaquiddick, a pregnant wife at home confined to bed rest.

As portrayed by Jason Clarke, the young senator is a venal, self-pitying coward, thoughtless and remorseless, ambition his only care. He treats loyalists and groupies with equal contempt, and as the weekend begins, he toasts them all for “wanting to prove yourselves worthy of . . . the Kennedy name.”

It’s clear the filmmakers are in on this joke.

We next see Kennedy leaving the party with the young Mary Jo Kopechne, who had worked for Bobby Kennedy and was still mourning his death. The film depicts Ted as drinking and driving before his black Oldsmobile 88 flies off a small wooden bridge and into a pond, crash-landing upside down.

According to contemporaneous accounts, the tide was dead low, the water only 5 or 6 feet deep. Both of the passenger-side windows were blown out. Kennedy later testified that Mary Jo might have been hitting or kicking him in her frantic struggle to escape. He claimed to have gone back under for her six or seven times but there is no proof. He was seen at 2:25 a.m. in dry clothes by a hotel desk clerk.

When Mary Jo’s body was recovered the next morning, it appeared that she died not of drowning but suffocation. She likely lived for hours. There she had been, her head and neck jammed at a sharp angle up against the foot board, gasping through a small air pocket. Was she wondering where Kennedy was? Was she convinced he was on the verge of coming back for her? That he had gone to get help?

After all, who would leave someone in this situation alone? Least of all someone who had suffered so much loss so young?

Ted Kennedy passed by nearby lighted homes and the local fire department as he walked back to his inn, away from the pond he’d later claim was deep and at high tide. He slept that night as Mary Jo took her last breaths.

The next morning, Ted refused to appear at the scene when summoned, demanding that the chief of police come down to the station. There, the chief finds Kennedy behind the cop’s own desk, reading a carefully worded statement. He doesn’t mention Mary Jo by her full name because he doesn’t know how to spell “Kopechne.”

Ten hours had passed since the car went in the water.

But Ted’s only concern is that he’ll never be president. Criminal charges don’t concern him, nor does he ever consider he might go to prison. He is, after all, a Kennedy.

Ted flees the island, helps block an autopsy, and attends Mary Jo’s funeral wearing a fake neck brace. For a time, he considers blaming the dead girl and telling the police that she was driving. Instead he blames the bridge, he claims exhaustion, he tells The New York Times he has a concussion and is on sedatives until The Times reporter informs him no doctor would ever give sedatives to someone who’s concussed.

And Ted feels sorry for himself all over again. Ted the eternal screw-up.

The film’s one flaw is, ironically, the glancing depiction of the women here. Mary Jo, played by Kate Mara, is never really fleshed out: She is The Girl, a young blonde who is very serious and very starstruck, but not much more. And Ted’s wife Joan — who was bullied by the family into calling Mary Jo’s parents and invoking Kennedy family tragedy to keep them under their control, and who suffered a miscarriage weeks later — appears onscreen for mere seconds, but speaking for us all when she says, “Go f–k yourself, Teddy.”

In the end, Ted Kennedy pled to nothing more than leaving the scene of an accident and received a suspended sentence of two months’ jail time. He would never be president, but he spent the rest of his life held in high esteem by the Democratic party. When he died in 2009, Chappaquiddick and Mary Jo Kopechne were barely mentioned. Instead he was canonized by the Senate as its Liberal Lion, a fighter for the poor, the dispossessed and, yes, women.

This film, in this #MeToo era, should begin to change all that. It should begin a new conversation about the Kennedy family in American life.