This isn't a professional view, but for a real fix this sounds like something that should be referred to a therapist if you have one. When you are sleeping your mind is taking the opportunity to go places you won't let it deal with otherwise.
Immediate patchwork fixes. 1) Try sleeping with a small light on, so if you awake you can see he's not there. 2) A stuffed animal. Those things are great! 3) Have you tried playing soft relaxing music that you like, and leaving it on when you go to bed? 4) Do you have a pet - a dog or cat. Both of those get up and roam around at night and you may be triggering because of that. If you have pets, try closing them out of your room.
If you wake up in a terror I would say it's important to not wake up in the dark fumbling for the lights when you "know" they will show he's right there. You need to be able to awake, look around, and then focus on what's real. The feel of the floor under your feet, your hands on the covers, the taste of a glass of water perhaps. Breathe slowly through your nose and feel the air. Perhaps make a list of things you like or that bring you happiness, and keep it by your bed. Or pictures of special happy occasions.
Just some ideas. Hang in there - this is a rough one.
Nobody living can ever stop me
As I go walking my freedom highway.
Nobody living can make me turn back:
This land was made for you and me. (Woody Guthrie)