A drunken motorist drove more than 90 mph the wrong way on the Long Island Expressway Thursday in Suffolk, unaware that a sheriff’s cruiser with lights flashing was pursuing her at about 120 mph, just to catch up, authorities said.

Christine Sandolo, 30, of Coram, was going west in the eastbound HOV lane at about 2:30 a.m. near Exit 62, Waverly Avenue, where Deputy Sheriff Thomas Young was watching traffic on the eastbound service road as part of the state’s Stop DWI program.

Putting on his lights and sirens, he pursued her for about 45 seconds, and they passed about 20 vehicles before she pulled to the shoulder about a mile and 45 seconds later, Young said.

“When it’s a matter of seconds that could mean she could crash into anybody, it seemed like an eternity to me,” Young said. “She didn’t seem to realize ‘Oh, I’m on the wrong side of the highway.’ ”

Sandolo was charged with DWI, reckless endangerment and multiple vehicle and traffic infractions, officials said. Sandolo was also driving without a license, which had expired during the summer, he said.

She was arraigned Thursday in First District Court in Central Islip and bail was set at $7,500 bond or $1,500 cash. It was unclear if she had an attorney.

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Young said Sandolo had a “glassy look.” She told him she was getting off work as manager of a Patchogue restaurant and had two beers, the deputy said.

She was going home to Coram, but she couldn’t explain why she was going west instead of north, the deputy said. It was also unclear exactly how she made her way onto the wrong side of the expressway, Young said.

Young, who was assigned full time to the Stop DWI program in April, said this was his second wrong-way driver this year.

“People were making a concerted effort to get out of her way,” Young said. “My primary concern was she was going to crest a hill, even the slightest hill, and somebody wasn’t going to see her.”

He said he’s glad he prevented a possible tragedy: “The sense of urgency to stop her was indescribable.”