NYC- Aspiring pop star Diana Bianchi – the 19-year-old Hamptons native at the center of architect Peter Cook’s nasty split from wife Christie Brinkley – has a lot to sing about.

But can she carry a tune?

Yesterday a professional music manager told Lowdown that, once the dust settles, Bianchi should consider another occupation.

“A couple of weeks ago, she met producer Darren Gold, one of my friends,” said Jarred Weisfeld of 845 Entertainment, a music-distribution company. “She was singing for him and said she wanted a record deal. Darren gave her my cell phone, and she called and sang the Musiq Soulchild song ‘Just Friends’ into my voice-mail.

“It was the worst thing I’ve ever heard. I couldn’t hit delete quick enough! Then Darren called me today and was like, ‘That girl who sang into your voice-mail is in the paper this morning.'”

Bianchi’s lawyer, Joe Tacopina, disputed Weisfeld’s account. “I found that story has no credibility at all. I confirmed that that did not happen. She is a 19-year-old kid.”

Tacopina added: “All I will say regarding her singing is she received a voice scholarship award by the Chorale Society of the Hamptons. She’s apparently a very talented singer.”

He wasn’t finished.

“How does this manager even know it was her?” Tacopina demanded. “I also find it particularly distasteful that people feel they need to further victimize Diana at this particular moment.”

Told of Tacopina’s remarks, Weisfeld responded: “Distasteful is cheating with a man married to Christie Brinkley. Poor music is poor music.”

Double meow.

Additional story: Christie Brinkley’s mom is spitting mad at her scoundrel son-in-law Peter Cook – calling him “a no-good SOB” for allegedly cheating on his supermodel wife with his teenage assistant.

“He is the guilty man here. She is fine – she is doing great,” Marjorie Brinkley told Star magazine in an exclusive interview. “He’s a no-good SOB. We are all completely devastated, as Christie is. It is shocking how this could happen.”

Cook, a top architect, and cover girl Brinkley separated last week and the sordid details of his seduction of 19-year-old aspiring Long Island singer Diana Bianchi quickly emerged.

Christie “is too great for him, and he has now shown his true colors,” Marjorie Brinkley told Star.

“Christie is a very strong, good girl and that is why it is so shocking. She did everything for him.”

Brinkley’s friends told the Daily News she could attack her straying husband with a vengeance – but won’t wage a vindictive public battle for the sake of her children.

“She could make mincemeat out of him, if she wanted,” a friend told The News.

But she probably won’t, sources close to the beauty add, because Brinkley is “all about” her three children, Alexa Ray, her daughter with Billy Joel; Sailor Lee, 8, her daughter with Cook, and Jack, 10, her son by Richard Taubman.

“The most important thing to her is her kids,” said another close friend.

The 52-year-old model was “devastated and shocked” by sordid revelations that Cook, 47, bedded a teenage aspiring singer he hired to work at his Long Island architecture firm, friends said.

But “she’s not going to curl up into a ball,” one friend said.

Another pal said, “She was so blind-sided by this. But she’s a very strong woman.”

Indeed, Cook was cozying up to Brinkley at the premiere of Ed Burns’ “The Groomsmen” in the Hamptons just four weeks ago, and at The Beacon restaurant in Sag Harbor, L.I., the week after.

Pals describe Brinkley as “beautiful inside and out” – but tough.

“She’s a fighter,” one friend said. “She’s like a ray of sunshine. She’s the strongest woman I know.”

Brinkley was shielding her two younger children from the media onslaught yesterday, trying to provide them with a normal, fun day outside the Hamptons.

“She’s always running around with her children. It was a fabulous family,” said Ruth Vered, owner of the Vered Gallery and a member of the board of Brinkley’s and Cook’s anti-nuke STAR Foundation.

“She is very serious – she makes things happen. She’s no playgirl, and I think [Cook] is a jerk.”

Joan Jedell, publisher of the Hampton Sheet magazine, told The News she once asked Brinkley what was the key to her successful marriage.

Brinkley answered: “Honesty.”