Selma Blair Threatens Lawsuit -- You Screwed Me Over, Charlie Sheen!

Selma Blair has called in the legal hounds ... threatening Charlie Sheen and Lionsgate Entertainment with a retaliation lawsuit after getting the ax on "Anger Management."

Sources connected with the show tell TMZ ... Selma believes she had a big fat target on her forehead after daring to criticize Charlie for being a slacker. She repeatedly complained to the crew that everyone had to sit around and wait while Charlie sat in his trailer and learned his lines.

Charlie got wind of Selma's beef and she believes that's when the die was cast. Our sources say Selma's now demanding the $1.2 mil she would have made if she would have continued working ... and if she doesn't get it she's filing a lawsuit.

Sources tell TMZ ... of the 12 scenes per show, Selma was only in 3 or 4. Charlie was in all 12 and required to memorize 44 to 48 pages of dialogue per show. One source said candidly, "When you work 12 hours a day and have 3 girlfriends at home, it's hard to memorize all the lines for tomorrow."

As for the claim of wrongful termination based on retaliation ... our sources acknowledge, when Charlie heard Selma was trashing him he was pissed, but the decision had already been made to write her off the show, because "America didn't want to see Charlie with just one girlfriend."

But here's the thing ... One very well placed source tells TMZ ... the plan was to phase Selma out over 8 episodes. After Charlie heard Selma was bitching about him, "That process was accelerated."

We're told lawyers for Lionsgate and Selma are currently talking ... trying to reach a settlement.