HOME ALONE star MACAULAY CULKIN has a new girlfriend, but pals fear the relationship will cause the troubled actor more heartache and send him off the deep end!

Culkin, 32, now shares his SoHo loft with rocker Jordana “Binki” Shapiro, who was previously involved with a friend of Mac’s and remains super-close to him.

“Binki used to date Mac’s good pal Adam Green of the band The Moldy Peaches,” said a close pal.

“She and Adam have formed a group, and things have gotten complicated because Mac wants to join it as a backup singer.”

Unfortunately, the former child star doesn’t seem able to carry a tune.

“Mac wants to start a new career as a singer and has been taking lessons,” said the pal. “But he can’t hold a note. He’s not good enough to perform professionally, and both Adam and Binki know it.”

When Binki broke the news to Culkin, he flipped out, says the source.

“Mac got into a huge argument with Binki and Adam,” revealed the pal. “He screamed at them, ‘I’m a damn good singer! I’ve been taking lessons for almost two years!’ ”

Now Binki, 24, who earned raves for her album with the band Little Joy, is worried this set­back will push Mac over the edge, says the source. As The ENQUIRER pre­viously reported, the troubled actor has battled addic­tions to heroin and prescription painkillers. Culkin’s representative has de­nied the star’s drug addiction.

“Binki fears that being rejected as a backup singer could make Mac turn to hard drugs once again,” said the pal.