All by herself, indeed.

Levi Johnston's on-again engagement to Bristol Palin -- announced in the new issue of Us Weekly -- is hitting Kathy Griffin hard!

The comic, 49, took Johnston, 20, as her date to the Teen Choice Awards last year, and apparently hasn't gotten over their brief time together.

In this hilarious video, a devastated Griffin sobs as she caresses and rips out pages from Johnston's issue of Playgirl. Her sad musical soundtrack: Celine Dion's cover of Eric Carmen's tearjerking ballad "All By Myself."

Griffin first shared her heartbreak via Twitter on Wednesday, when Us Weekly's exclusive interview with Johnston and Palin, 19, first hit newsstands and the web. "Oh y did I trust my heart 2 a 19 yr old ice-fisherman/babydaddy from Wasila?...Like Britney I'm putting myself on a 5150 psych hold."

But all is not lost for Griffin: at the tail end of the clip, she reveals that she has another young Hollywood hunk in her sights.

Find out who it is -- watch the clip now (above)!