Ray J -- 911 Call for Suicidal Girlfriend ... 'She Might Kill Me First'

Ray J was afraid his girlfriend was going to pull a murder-suicide -- offing him and then herself -- just days after rapper Earl Hayes did the same ... at least according to his 911 call that day.

TMZ broke the story ... Ray J freaked last month when he broke up with Princess Love, and he says she threatened to kill herself with a gun.

We've obtained the 911 call he made ... begging the dispatcher to send police to check on Princess. He repeatedly mentioned the Hayes murder-suicide -- and that he attempted, but failed, to take Love's gun.

One weird thing to listen for -- Ray J can't seem to decide if he left Princess in the house out of fear, or because ... "I gotta go shoot a television show."