Hugs to you Skeeter

My advice would be to turn all the lights on, and maybe put on music or the tv (I turn on the tv, music freaks me out when I'm in a similar situation) and try to breathe slowly. Even if you feel really scared try to keep reminding yourself, as you do in your post, that no real harm will come to you. Because it won't

I also have problems with nightmares and waking up in the middle of the night feeling like some sort of devilish creature is after me...Especially if I'm alone or I have spent a while being alone...I think it's a sort of symptom of not feeling safe in your own skin in a way..At least that's the most likely explanation for me.

Definitely talk to your therapist about it. And please make sure you don't keep the knife in your bed!
I hope you feel better soon and that the sun will rise soon where you are
(Those first rays of the sun after such a night..Think about the sun )