A deranged boyfriend fatally slit his girlfriend’s throat inside their Brooklyn apartment early Sunday morning – and then calmly lounged on a sofa as he waited for cops to arrive, sources said.
Officers found the 41-year-old victim with multiple stab wounds and her throat slashed after they were called for an assault in progress at the intersection of Cooper Street and Irving Avenue in the hip nabe of Bushwick around 8:50 a.m., police said.
Responding cops had heard the woman crying for help from a nearby townhouse, saying she was being stabbed, according to sources…