N.Y. Civil Practice Law & Rules Law § 4502 (2026)

§ 4502. Spouse. (a) Incompetency where issue adultery. A husband or
wife is not competent to testify against the other in an action founded
upon adultery, except to prove the marriage, disprove the adultery, or
disprove a defense after evidence has been introduced tending to prove
such defense.
  (b) Confidential communication privileged. A husband or wife shall not
be required, or, without consent of the other if living, allowed, to
disclose a confidential communication made by one to the other during
marriage.