Help me deal with psychological horror.

Take small breaks during playing. I just pause the game and allow myself to calm down before moving on.

but lately, games and movies involving supernatural entities and jump scares have started scaring me,

Yes I can tell one thing from personal experience, suck it up when you go through it the first time with friends/family and REPEAT it alone.

Example, go watch a movie of Conjuring 2 in Cinema (bloody hell who gets scared in Cinema with so many people with you?) and then you watch it alone at home.

Now I don't have any horror anymore =s

Well, jump scares are different thing though. I can't avoid it although I watch it in Cinema.

I know the feeling. When I started playing Amnesia and Outlast, I could barely play for 15 minutes before needing a break. Been playing those games in short bursts, though the bursts have gotten a bit longer as I go along, so 30 minutes at a stretch is now normal, and an hour is doable depending on how intense the game is

I try to find make humor out of little things in games, which is much easier if the game has physics. Make an object your friend and carry it with you is also nice.

That's all part of the experience, sadly it will diminish with the amount of games/movies/stuff in RL you consume, but as already mentioned watching some behind the scenes stuff will pretty much destroy the illusion.

But if it really affects you in a way that your sanity seriously starts to crumble because of it, you should just stop ;>.

Well maybe you just have to accept the fact that you can't handle these kinds of movies or games. Or you can try to visit a therapist, they can help people to get over any fobia and fears. I believe it is worth trying if you really want to watch such movies and play those games. Just don't be ashamed for going there, there is no need to feel bad for going to a professional to help you get rid of something that bothers you. I wish you the best pal.

Now that you have accepted it and know what to expect it shouldn't be as bad as before. There are different levels of thriller or horror. It's normal to be afraid. There are 7bn people on the planet, sometimes it's best not to think too much.

Hmm, I also having similar condition, maybe it relate with getting older..?
As a child I consume so many horror movie, but now in several years before I just play:

• Corpse Party:the sound effect is terrifying...
• PT: give up, too scary, I uncomfortable with setting that looks my safe comfort zone, home, moreover it has loop. Ended up watching let's play...
• Year Walk: my heart beating so fast while playing this, the atmosphere so scary

For summary maybe as we getting older, I assume psychological horror is kind of something that threaten our stable life... If you really want to play it, maybe play in big room like living room, with friends, then aftermath play/do something you like ^^ (for me I read romance comic, my head is busy shipping XD)

I find it hard to play horror games unless there's a story I care about.

Amnesia: The Dark Descent and SOMA are two examples. I got the OH NO NO I'M NOT DEALING WITH THIS vibe, except then there's something interesting to make it worth it.

Whereas I can't finish Alien Isolation. Don't get me wrong, it's brilliant. And that's the problem. The gameplay is so spot on that I'm not willing to stay up at night because the science fiction monster scared me...not without something in the story which is intellectually interesting. I'm not saying the story also isn't good, just that it doesn't pique my interest in the way that Amnesia hits me in the Lovecraft or SOMA makes me absolutely hate the player character in a way that I can't wait to see him cry like the little child I am for being too afraid to play Alien.

Yeah, I'm a wuss. I also couldn't sleep after watching The Conjuring, and I could swear that the rubber duck in my buddy's bathroom was alive when I had to take a pee break. Certain other factors may have been in play in the latter case. But I also wasn't the one in the room who jumped up and screamed after the clapping game scene.

Looking for good professional help would be a good idea. I've never been to much into horror games and such, because I feel powerless or something like that.

Well, I usually brave horror games myself, even if I'll end up thinking of the game for days lol. That's what I did with Fatal Frame series, and have never regretted my decision since.

Since it seems you have some trouble with the immersion itself, there are several things that you can do to tone down your immersion.

• Friends
  Bringing a friend or two to watch you playing might make you feel braver than before.

• Headphones
  Headphones are great for immersion. Try not to use one if you really can't handle the sound.

• Time of the Day
  I found that most of the time, playing during the day might help you to be able to play horror games.

Personally, I try to be immersed in horror games. Consequently, I've done exactly the opposite of what I advised above. Dealing with these kinds of psychological things differ from person to person, but you might try "breaking down" the immersion gradually and see how it goes.

Hope it helps. :D