In terms of the incident, the violent attack where he grabbed her by the throat and threw her to the ground happened with an interval between her stabbing him. I think if she had stabbed him at that point the jury would have seen it as loss of control, self defence and manslaughter rather than murder. However, they were still in a group where the friends pulled him off her and calmed the situation down. They all then got back into the car where the defendant was in the passenger seat, her attacker (I can’t refer to him as a victim..) in the driver seat, the friends in the back seat. The attacker put his hand on her breast, she swung at him with the knife in hand delivering a single fatal wound to chest.
I don't think that interval - how long was it? Half an hour? Ten minutes? - makes all that much difference. He tried to kill her, she must have been in shock and terrified, adrenaline coursing through her, plus she had PTSD from a prior rape and possibly from escaping a violent father, too.
This woman has spent her life being attacked by men, witnessing/experiencing male violence. I'm not at all surprised she lashed out at a man who grabbed her by the throat and then grabbed her breast. Even if there was an interval between the violent attack and the sexual assault.