MTO WORLD EXCLUSIVE: It Finally Happened . . . Diddy Proposed To His LONGTIME Girlfriend Cassie . . . She Announced Their ENGAGEMENT On Instagram!! (Pics Of The Ring)

: Sean “Diddy” Combs is the QUINTESSENTIAL bachelor – and many thought he would NEVER settle down. Well they were all WRONG. MediaTakeOut.com learned that Diddy has made it official – he PROPOSED to his longtime GF Cassie.

Cassie announced the engagement and showed off the ring on Instagram yesterday:

Cassie and Diddy met ten years ago, when Diddy first heard Cassie’s first radio single, “Me & U,” and ended up releasing her first album on his label, Bad Boy Records. It evolved into romance but Diddy didn’t fess up about the relationship until 2012. Cassie’s been holding him down for a LONG time.