A man who allegedly sexually assaulted an 82-year-old woman inside her Lower East Side apartment was busted by cops on Friday, authorities said.

The suspect, 29-year-old David Alexander of the Bronx, allegedly broke into the woman’s apartment in the Rutgers Houses through an open door at about 6 p.m. on Tuesday, cops said.

He then grabbed her by the neck, groped her breasts and started to touch himself, police said.

Cops busted Alexander Friday and slapped him with assault, burglary, sex abuse and criminal obstruction of breathing charges, authorities said.