Last night’s finale of my formerly favorite show, “The Killing,” left me feeling like a Bernie Madoff victim.

Like every good Ponzi scheme, we loyalists invested every week, expecting a big payoff at the end — secure in the knowledge that it was all good, because we’d been getting very satisfying returns every week, so far.

But to end it all with a shooting and then a black screen? Bad. Very bad.

“There hasn’t been a cop-out like this since Tony Soprano!” screamed the Love Interest, who faithfully watched all 13 episodes with me.

And he was so right.

Not only did we not definitively find out who done it, but we were left with a scene stolen straight out of the “Sopranos” finale. Black screen, run credits, go home.

Are you kidding me?

We don’t even know if Richmond, after being shot by Belko, will even live to be tried in the next 13 episodes. And even that scene was a shot-for-shot knockoff of the real-life shooting by Jack Ruby, who also rushed through a phalanx of cops to shoot Lee Harvey Oswald.

After 13 weeks of perfectly crafted shows, we were handed a finale with cribbed scenes, missteps and errors.

For example, in what state is a cop allowed to go to a councilman’s apartment and berate him about an active case, accuse him and walk out? Even before he was arrested, the councilman would have been granted a mistrial! (And what about the fact that Councilman Richmond didn’t immediately call his lawyer?)

And what about Richmond’s arrest for murder at the big public rally? Elected officials are always given the courtesy of turning themselves in — especially if they aren’t a flight risk.

And those two Stan Larsen (the dead girl’s dad) scenes looked like they were written by someone who’d never watched the show.

How are we supposed to believe that the pregnant wife of Bennet Ahmed could speak to Stan in the hospital without recognizing him as the father of the dead girl and the man who nearly beat her husband to death?

What about the fact that Stan doesn’t even tell his wife, who walked out because of it, that, no, he didn’t gamble all their money away, but that he used it to buy her a house?

But the thing that ticked us off the most was that cheap shot closing scene of Holder getting into a car and telling the unseen driver: “The photo worked.”

So he and a connection (the mayor?) are behind it all? Right. That’s as plausible as 50 straight days of sunshine in Seattle.

So, will I watch the show next season? Is the Pope Catholic? One bad chapter doesn’t mean I won’t keep reading a great book.