By Breaking Celebrity News Staff

Britney Spears is happy and engaged, but her ex-husband, Jason Alexander exclusively tells Star magazine that he doesn't see it working out.

Alexander -- who married the Oops!...I Did It Again singer in January 2004 (the union was annulled after just 55 hours) -- calls her relationship with fiancé Jason Trawick "a complete sham," and claims Trawick, 40, "will end up hurting" Spears, 30.

He told Star exclusively, “If they actually get married, it will probably only last for a year two, but not much longer than that.”

Alexander told Star he feels the pop singer must have felt between a rock and a hard place when she accepted the talent agent’s marriage proposal on December 15. Th