I apologize if this is in the wrong place, but this is my first time really opening up about this.

I've always had this feeling that someone else is inside me. Like it's me...but it's NOT me. I always hear his voice inside my head, and he's always telling me things that I should do (I am female by the way). They are never good things.

He has a name...I'm sorry, I don't want to tell, and I never seem to find myself in control. I don't have control over when he shows himself, and when he does it's like I'm watching a movie. I do things and say things that I don't have control over. It's as if I'm the consciousness and he's the actual me. He tends to show more when I'm feeling jealous or angry, and he's not nice. He enjoys harming people. Whenever the smallest thing upsets me or whenever I see someone in pain/trouble I can feel him trying to take control, and I just want to get away from people as quickly as possible before he can harm them. There have even been periods where I literally do not remember things I have done while he's showing.

Because of this, I haven't left my house in a while (except for appointments) because I want to protect people.
I have conversations with him on a regular basis, and there have been times where I have pleaded for him to stay calm and let me stay in control, and to handle things.

This has been going on for so long that I no longer have any "real" emotion anymore. I just don't care about anything. I can't really cry, I can't smile, even laughing is rare. I don't even feel guilt. If I do, I'm tortured by him. He calls me a coward, and calls me weak for showing emotion towards people. He tells me to self-harm so he can see it and be excited by it.
I don't want to hurt anyone, but I'm beginning to not care.

My doctors aren't telling me what this is because they're not completely sure and are suggesting starting some kind of treatment for this, but as much as he hurts me....I DON'T want him to go away, because if he disappears, then a part of me would be missing and it just wouldn't be the same. Like there would be a huge whole in my body that couldn't be filled. If he goes, then I go too.

I'm sorry if I'm confusing anyone, but that is the jist of things.
I'm not really good at explaining troubling things.... :c
But any advice would be appreciated.
Thanks~