Multiple Personalities Support Group
Dissociative identity disorder is a diagnosis described as the existence in an individual of two or more distinct identities or personalities, each with its own pattern of perceiving and interacting with the environment. At least two of these personalities are considered to routinely take control of the individual's behavior, and there is also some associated memory loss,...
If you really believe your alter is in control and don't have the ability to negotiate with him/her/it...and you believe you are in immediate danger, then taking a few days in a hospital is not a bad idea.
Cutting is like a form of self medication, much like heroin addict trying to treat anxiety. There are many ways to treat trauma and process emotions in healthy ways.
I recommend you look at this website on CPTSD:
http://pete-walker.com/13StepsManageFlashbacks.htm
If all else fail a self inflicted cut and certain other things will keep you alive especially if in tough environments.