Melvin James, 36, launched the assault on Lynette James after fatally wounding his sister, Anne-Marie, at their flat in Wolverhampton.
Police were called and officers initially attempted to Taser the attacker before fleeing the high-rise, 'terrified' for their lives.
Giving a harrowing account, Mrs James said she was about to have a shower when she heard Anne-Marie call out to her.
Her evidence, read by Black Country senior coroner Zafar Siddique, said: 'I sensed and felt something was seriously wrong.
'I decided to run into the lounge and call the concierge from the phone. I saw Melvin by the kitchen and he ripped the phone off the wall.'
She added: 'His eyes were red, fixed and he was staring at me. He plunged the knife into me, again and again.
'I said, "I love you, son".'
She fled to the bathroom, locking the door and ringing 999 to tell police she had been stabbed and feared she was 'slipping away'.
The mother-of-four added: 'I said "I'm going to die, my son has stabbed me and my daughter is on the floor".'
Mrs James, then 59, described how the weekend before, her son and daughter were 'happy and laughing'.
But the night before the incident, unemployed Mr James was in a 'strange mood'.
The next morning, Mrs James noticed her son had opened all the windows and appeared 'hot and sweating'.
She and her daughter 'agreed something was wrong with Melvin... and I said we'll go see my doctor and get some advice'.
Police were initially called after a neighbour reported 'horrific sounds' from the flat, with Mrs James's panicked call coming soon after.
The response officers first on the scene Tasered and then batoned Mr James but were forced to retreat.
Specialist armed units rushed to the tower block, and smashed a hole in the door large enough to squeeze through - throwing two stun grenades through the opening.
But as one officer managed to step inside, he recoiled as a blood-spattered Mr James came along the flat's hallway towards them carrying a knife.
PC Panter, of West Midlands Police, told the inquest: 'I put my (weapon) selector to 'fire', my finger on the trigger. I was almost certain I would have to take a shot.'
But the officer said he then decided to take the less-lethal option.
'So, I dropped my carbine, drew my Taser, and took the shot.'
While Mr James was down, other armed officers rushed in to disarm and then handcuff him.
As police turned him over, they noticed his 'serious abdominal injuries' and handed him over to medics.
The inquest, in Oldbury, West Midlands, also heard from younger brother Leon James.
In February 2017 he collected his older brother from hospital in Scotland, after an admission for a 'medical episode', and brought him back to live at Mrs James' home.
Mr Siddique said: 'He was taken to the Royal Edinburgh Hospital, initially as a voluntary patient.
'He made some progress and was discharged on February 10, with a diagnosis of drug-induced psychosis.'
The inquest continues. Just sad.
