... scream like a little girl whenever a monster spawned close by?
No.
... boast to others that the game wasn't that scary only to shit your pants shortly thereafter?
New game, and haven't told anyone yet about it.
... at any point have to quit the game to give your heart time to slow down and/or your hands to stop shaking?
So-so, fighting a cold, and some was getting a tad tense.
... die more than once - because you were killed by the same monster?
Yeah, trying to get away from the monster and out of the sewers. It was hinted to close the doors and then run up the ladder. That didn't work. panicked too much, so I just opened the doors and ran to the ladder as fast as I could. no more monster
... regret that you turned the handle and allowed a certain someone to talk to you?
no
... feel too frightened to open a door, because you thought a monster might be on the other side?
so-so, maybe a few seconds, but I knew I had to go on.
... feel too frightened to pick up what you had come for, because you knew a monster might spawn?
Best I can say is that glass jar to get acid. I thought after pouring the acid on the lock, I had to go back for more. I did, but was getting a bit tense and scary. I later discovered you couldn't get more acid, and the hammer was the answer to breaking off the rest of the lock.
... pass out from low sanity while waiting for a monster to disappear?
I had to wait in a room where there were dead bodies (after getting blood from a body on a table), my player actually started to turn sideways and I had to keep him from fainting.
... pass out from low sanity while hiding from a monster that wasn’t even there?
no.
... attempt to flee from a monster only to run right smack into it?
(edit: I read this wrong. I thought it said, I got too scared and ended up running into some object or wall, so this answer doesn't entirely apply to the question)
somewhat. monster in the prision area saw me and I ran back the other way, but it was pitch black, couldn't see a thing. I was amazed that I found myself somewhere else, and the monster disappeared.
then I'm like, dang it, I have to retrace where I've been.
... jump off the window ledge in the study, just to see what would happen?
no. sort of wanted to, but didn't.
... jump off the window ledge in the study and then laugh like a maniac when you died from the fall?
no
... spend a few minutes giggling insanely as you threw various objects into the vat of acid?
did I laugh? or just smile? it was cool throwing in that pig, and some bottles, etc.
... pick a hiding spot and realize too late that it wasn’t a very good hiding spot?
one time, I think again, in the prison area. monster saw me, it was a dark area, but clearly a dead end. monster came around and killed me.
... play through the game multiple times only to find out to your unpleasant surprise that things were slightly different that time around?
first time playing this game, and not finished yet.
... go back to an earlier save and play an area over again because it was so damn much fun?
not yet
... frantically try to stop the elevator when things started to go south?
felt like it, but being sick, I am no fun. I was beginning to worry that I should stop it or something, but I just let that thing go.