Brook, 34, took to Twitter to break the sad news to her fans.
Deleting all photos of her ex-fiancee from her Instagram account, she wrote, "It's a sad Day but I wanted to share with you that David and I are no longer engaged."
Brook added, "I love and respect him and wish him all the best."
She also stepped out in Los Angeles without her engagement ring.
The couple had a whirlwind courtship after meeting on New Year's Eve and Mcintosh, who recently appeared on British reality TV show 'Big Brother', proposed in March.
No reason for her latest split has been given so far.
