Nick and Bobbi Kristina
Bobbi Kristina Brown and Nick Gordon argued hours before she was found unresponsive in the bath.
The couple had been partying with a friend on January 30 and when they returned to their Georgia home in the early hours of the following day, they had a heated conversation before going their separate ways.
Nick's mother Michelle said: "Nick walked away from the argument.
"He went to another bedroom to fall asleep. [Bobbi Kristina] went up to her room and drew a bath."
The couple's friend Max Lomas later found the 22-year-old aspiring singer unresponsive when a cable repair man arrived and needed access to her bedroom. Together, he and Nick administered CPR before paramedics arrived.
Michelle recalled during an interview on 'Dr. Phil': "Nicholas was able to do the CPR on her for 15 minutes.
"The police arrived, and they didn't help him. No one helped him until the EMTs got there."
And Nick has turned to alcohol and drugs in a bid to cope with his guilt from the incident, and agony over not being able to visit Bobbi Kristina, who remains in a medically induced coma at the Emory University Hospital.
Michelle said: "He has blamed himself for the condition she's in."
During the interview, host Dr. Phil McGraw persuaded Nick to check into rehab after hearing he has tried twice to take his own life.
Dr Phil said: "Nick, you're out of control. You've threatened suicide. You deserve to get some help because if you don't, you know you're going to wind up dead."
Nick - who checked into rehab last week - vowed: "I'll be clean, I'll be sober, I'll be a good person."