So, you were living in an abusive environment and were witness to violence. This is so traumatic for a child. It's a form of neglect for a parent to raise a child in that chaos and I'm very sorry you had to live like that. The world of imagination when a child has an abusive home becomes very real. Your fantasy world of these two 'friends' was like a protection. The alter ego friend, Jeff, is a dangerous friend though, wouldn't you agree?
For a lot of people in our situation, these imaginary friends and the created protected fantasy world begins to disappear as you age out and are out of the home and they are no longer needed. Why do you think you are still so entrenched in the imaginary?
Have you been through any form of therapy with a psychologist? I think that would be essential for you. Because you probably have a lot of unresolved feelings about your childhood. You also want to explore why Jeff, an extension of your OWN thoughts is sending a message to kill yourself. Are you depressed? This really warrants a deep dig with a psychologist to work through.
Generally, getting more and more engrossed in daily life usually helps the imaginary friends fade out. Letting go of past. Breaking habit of talking to them.
Would a therapist be something you'd consider?