Queens firefighters responding to a blaze last night found a stabbed woman who later died and her boyfriend trying to hang himself, authorities said.

The unidentified 30-year-old victim was on the bed in a basement apartment on 214th Place in Bayside at about 7:30 p.m.

“[Firefighters] opened a nearby closet and found the male attempting to hang himself,” said Queens DA Richard Brown.

The suspect, 56-year-old Suk Hyun Yoon, was busted and was in critical condition at Queens General Hospital.

“They were fighting all the time. She is gambler, and she always goes to gamble,” said landlord Yung Uk Kim, adding that Yoon owed $8,000 in back rent.

It wasn’t clear how the fire started. It caused minor damage.