Hi again, your experience with this particular entity sounds like my own with the demon/devil Asmodeus, very good at pretending to be others, hiding and gaslighting, very abusive, and frankly purely psychopathic. But I am in the process of learning to work with him. Over time I've become good at telling when he is up to his tricks and it sounds like you are in the process too of learning this yourself, which is good as knowledge is power. Now I get spirits say to me "how did you know that was really me" when they are faking... well it's "experience", haha. It's a shame to have to go through so much of this to know how to deal with it, but I assure you if you stick to your healing process you will figure it out and become the master of your own space.
It sounds like you've been through a lot and are a sensitive so you are going to be naturally more prone to these issues, but they won't kill you I promise
It may feel like it sometimes, but their power on the physical is actually pretty limited. They can really only hurt you as much as you are afraid of them, which is why it's important to master your fear. I learned that the hard way!