Capri Anderson made alarming allegations about that infamous night she spent with Charlie Sheen -- including claims of alleged drug use and abuse ... and she says she'll file a lawsuit today.
Anderson, who sat down with "Good Morning America," described Sheen snorting a "white powdery substance" and recounted the moment when she felt things took a turn for the worse, saying, "When I became really uncomfortable is when he put his hands around my neck."
Sources connected with Charlie say he did absolutely nothing violent.
Anderson -- who was there with her lawyer, Keith Davidson -- said she plans on filing a lawsuit in Los Angeles Superior Court.
UPDATE 9:10 AM PT -- We shot Capri and her lawyer heading into a law office, where the lawyer stated Capri plans on suing for battery and false imprisonment.