I am not adding any movies as examples because I don't want to set the tone of the answers.
shareIrreversible (2002)
shareThat's on effedupmovies.com if anyone wants to watch it. I saw it a few months ago.
shareThe Bourne Identity (2002) /tt0258463
shareSalo Or 120 Days Of Sodom may be the most sickening and pointless movie I’ve ever seen.
Maybe the point was that fascism and unlimited power are bad but NO KIDDING? You Don’t say?!?
Nobody needs 2hrs. of rape, torture and murder to know this.
Seriously, skip this movie. It’s perverted trash.
Completely with you on Salo. That movie is frequently placed on lists of the most disturbing movies of all the time but calling it a movie is a stretch when in reality it's an incoherent mashup of torture scenes and poor editing. There is virtually no "point" to the movie beyond what you've already described. Even A Serbian Film has some redeeming qualities as a black comedy with social commentary on those that consume depraved media, but Salo is simply trash.
shareANNIE.
shareWasn't cussing, but it had me on the edge of my theatre seat :
Jacob's Ladder
The Battle of Algiers
https://youtu.be/zpn4Htfrv88
The first movie that comes to mind when I think of edge-of-your-seat thrillers has been The Chaser (2008) since I first saw it; I know your topic is a bit less specific than that, so I'll list a few more on topic, although the aforementioned film is also totally on topic, btw...
No Country for Old Men (2007)
Nightcrawler (2014)
Misery (1990)
Maniac (2012)
The Living and the Dead (2006)
Oldboy (2003)
Take Shelter (2011)
Sleep Tight (2011)
Suddenly, Last Summer (1959)
Noroi (2005)
Splinter (2008)
All these got an 8/10+ from me. U.S. titles given only.