TMZ has obtained a police report filed by Michael on December 21. Lohan says, "My ex-fiance, Erin Muller, threatened me with a knife during an argument several months ago and I wish to pursue charges."
Lohan then goes on to say ... "I did not report this at the time because I wanted her to get help for her addictions."
So what changed for Michael? Well, for starters, Muller had him arrested on December 14 for allegedly violating a restraining order against her.
So much for addiction help.
UPDATE: Erin's lawyer is disputing Michael's allegations, telling TMZ she "did not threaten Michael Lohan with a knife."
The attorney also tells us that Michael "is starting to realize that Erin really doesn't want anything to do with him. He needs to take a hint and go away."