He said she had been planning to stage her first solo concert later this year. She was also a trained architect.
Hillary Obinna, another friend who sang alongside her, told the BBC he was told she had been asleep when “the snake bite woke her up”.
He said that two snakes were later found in the house.
She first sought treatment at a nearby clinic but they did not have any antivenom so she went to a hospital.
Ezugwu said he rushed to the hospital on Saturday after learning that she had been taken there. He said the hospital had one of the required antivenoms but not the other.
“While they were trying to stabilise her, she could not speak but she could make hand gestures. She was struggling to breathe,” he added.
Ezugwu said he drove out to search for the missing antivenom but returned to find that she had died. The BBC has asked the hospital for comment.
He said the entire choir went to the hospital that evening, “hoping that a miracle would happen”.
Obinna described Nwangene as “a very wonderful girl, she is humble – very intelligent and very talented”.
“Everybody is shattered. We could not sleep at night.”
Her death comes amid a renewed debate in Nigeria about the quality of healthcare and patient safety, following a series of allegations of medical negligence.
These include the recent death of novelist Chimamanda Ngozi Adichie’s 21-month-old son. The hospital in that case has denied any wrongdoing.
In response to the public outcry, Nigeria’s health minister has acknowledged “systemic challenges” in the health system and announced the creation of a national task force on “clinical governance and patient safety”.
Most snake bite victims in Nigeria are believed to live in rural areas and many Nigerians are shocked at Nwangene’s death in an upmarket part of the capital.
The World Health Organization (WHO) says venomous snakebites are a neglected public health issue in many tropical and subtropical countries.
In Africa, between 435,000 and 580,000 snakebites requiring treatment are recorded each year, according to the WHO. The burden falls mainly on women, children and farmers in rural communities, where health systems are weakest and medical resources limited.
Those bites cause about 30,000 deaths annually in sub-Saharan Africa, though some estimates suggest the real number is much higher.
Experts say the shortage of antivenom is a major reason the scale of the problem is hard to assess. It leads many bite victims to seek care from traditional healers, meaning cases often go unrecorded.
Even where antivenom is available, it is often too expensive, and storage is difficult because most antivenoms require refrigeration in areas with unreliable electricity.