A woman whose home sits on the border of New York and Connecticut was stunned to learn her neighbor owns half of her abode — because her bank failed to pay property taxes on the New York side, she told The Post.

Rosanne Di Guilio’s kitchen, living room and porch now belong to her neighbor Alethea Jacob, 52, who snatched up .2 acres of the half-acre plot for $275 at a county auction after it went into foreclosure in 2010.

“It’s sickening. She’s an opportunist. How do you sleep when you do something like this?” said Di Guilio, a 52-year-old electrical contractor who lives in Brewster, NY, or New Fairfield, Conn., depending on which side of the house she’s on.

Di Guilio, who is fighting the foreclosure in court, said Jacob demanded $150,000 when she tried to buy back the house after she learned of the tax snafu in 2013.

She insists Jacob schemed for access to her property to avoid fixing her own leaky septic tank.

“I believe she bought it to be able to use [my] septic. It would be thousands of dollars to fix her own,” fumed Di Guilio, who has owned the home since 1997.

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