Linah Keza, 29, a former Miss Africa contestant, was found dead in a pool of blood by neighbours who heard her screams.
Her daughter Holly was discovered crying beside her body as the attacker rushed out of her home.
Miss Keza's former boyfriend, named locally as club promoter David Kikawa, 38, was later arrested on suspicion of murder after handing himself in to police and remains in custody.
Friends said the killing came after months of rows between the on-off couple, who were well known on London's African party scene.
A police panic alarm was installed at Miss Keza's rented first-floor flat in Leyton, East London. Relatives said her ex-boyfriend, who is Holly's father, was 'jealous and possessive'.
Last night, the Metropolitan Police alerted the Independent Police Complaints Commission over fears it could have done more to protect the victim.
Officers were called to Miss Keza's home at 4.30am on Wednesday by neighbours who heard screaming and thumping.
They discovered the pastor's daughter had been viciously attacked.
One neighbour described how he was confronted by the killer when he broke down the front door of the Rwanda-born model's flat.
He said: 'I was outside and I heard some shouting and screaming and I ran to the door. A woman was saying,"Kick the door in", so I did and came face to face with the guy.
'I could see the woman, there was lots of blood and she was lying half in the bedroom and half out. The little girl was next to her.
'I asked the man what he was doing and told him if he wanted to fight someone, he should fight me.
He went as if to fight me but he just ran out of the building. I tried to help the woman but there was no pulse. The little girl was just standing there, it looked like she was in shock.'
Neighbours described Miss Keza as an 'extremely loving mother' and said she and her young daughter were 'inseparable'.
More than a thousand people joined a Facebook page paying tribute.
Many posted photographs of Miss Keza, who worked as a model after studying social work at the University of Wolverhampton.
Her ex-boyfriend, whom she met four years ago, was an extrovert nightclub promoter who posted dozens of pictures of his champagne-fuelled lifestyle online.
Neighbours said he was seen regularly at the flat until about two weeks ago.
Miss Keza's relatives accused police of failing the young woman as they arranged for her body to be flown back to Rwanda for burial. Her daughter has been temporarily taken into care by the local authority.
Her cousin Herbert Muhire, who lives in Rwanda, said she suffered a 'gruesome death'. He added: 'She had a panic button in the house. David was the father of their child, they lived together but had separated a few months ago.
'Having a child together meant they were in close contact and she wanted to make up and get married.
'But he was jealous and possessive and would tell her not to see anyone and not to greet anyone and not to go to parties.
With it being a domestic dispute she did not want to talk openly about it.' Make-up artist Bella Bordianu, who worked with Miss Keza, said: 'She was very sweet and always smiling. She had a beautiful smile.
Photographer Fabrice Rizzato said: 'Linah was very kind, very professional, very beautiful and very calm – I am shocked at the news, she was a dignified and kind person.'