Robert F. Kennedy Jr.’s estranged wife, Mary, who battled her husband’s rumored philandering by turning to alcohol and prescription drugs, hanged herself in a barn on their Westchester estate yesterday, sources told The Post.

The 52-year-old mother of four — the latest victim of a family dynasty cursed with tragedies — may have taken her own life because she was haunted by her broken marriage, her friends lamented.