TWO children were woken in the middle of the night by their mother's screams and found her covered in blood, the High Court was told yesterday. The court heard Wong Mei-so was stabbed in her sleep by her ''good friend'' Lai Man-cheong, 50, because he suspected her of seeing another man. Lai, a hawker, has pleaded not guilty to the murder of Wong, who was in her late 30s, and is being tried by a jury before Mr Justice Sears. Lai, who claimed he had no intention of killing Wong but was just trying to teach her a lesson, said in his statement they had a quarrel and he had contemplated stabbing himself and setting himself on fire. In her opening address, Senior Crown Counsel Diane Crebbin said Lai had shared a two-bedroom Tai Po flat with Wong, whose husband died in 1990, and her two daughters since January last year. On October 16 last year, Wong and the two girls, aged 11 and nine, went to bed at about 10.30 pm, leaving Lai watching television in the sitting room. At about 2.50 am, the children asleep in the bottom bunk bed were woken by their mother's screams, and then saw Lai jump onto the floor from the top bunk where their mother slept, and run out of the room, Ms Crebbin said. Wong climbed down from the bed and went to the bathroom where the girls, who followed her, noticed her abdomen was covered in blood. She told the children to call the police but Lai pulled out the telephone line, the court heard. One of the girls ran to the window and cried for help while the other ran to the door also shouting for assistance. Their cries alerted a passer-by who called the police. When the police arrived, they found Wong lying on the sofa bleeding from a wound to her waist. They also noticed Lai holding a scissor blade and he admitted stabbing Wong, Ms Crebbin said. Wong was taken to hospital where she was found to be suffering from a stab wound to the abdomen. She died two days later. Police officers at the Tai Po flat found the other scissor blade and a bucket containing liquid later found to be methanol, a type of inflammable alcohol. When questioned, Lai described his relationship with Wong as one of ''good friends'' and told police that on the day before the stabbing, Wong left home early and did not return until after 10 pm, the court heard. She refused to tell him who she had been seeing but he suspected she was with another man. He went to bed feeling aggrieved and at about 2.45 am went to the kitchen where he picked up a 23-centimetre-long scissor blade and stabbed her once in the waist while she was sleeping, the jury was told. He claimed he just wanted her to feel pain and that the stabbing took place in a fit of anger. The hearing continues.