Sleep is a joke after what you saw, regardless of what you try to tell yourself as you lie awake in the dark. Your mom used to be really into affirmations, so you try repeating some of them in your head to see if it helps.
"I'm safe now."
"I was safe the whole time."
"There's no reason to be afraid. I'm in charge of my own life."
They should be reassuring, but they feel more comical than anything else. Every shadow that so much as flickers with the passing of a car causes you to flinch, and every creak in the floorboards sounds exactly like a footstep bearing Rex's weight.
It's only a matter of time before you accept that sleep isn't coming and grab your phone so you can engage your senses and mind in something else.