One scene wrecked the whole movie for everyone

Rating: 8/10 (26 November 2017)

When I first watched this movie I liked all but one scene which I found took from the movie. I watch the movie unlike most on here that rated Al 1 with zero expectations and was very much so enjoying it until the scene that I hate. I just rewatched the movie now and still can't believe that scene maybe even more so now. And so I feel compelled to write a review. Even searching now I see that even critics criticize this scene for single-handedly ruining the movie.
Basically the movie is a showdown between a psycho killer and an average but crafty southern ex vet. They do a very good job executing this to the point where you are literally on the edge of your seat for some parts. Javier Bardem helps this by playing his part masterfully. All actors in this film were good but he takes it to a new level. I'm gonna even call his character one of the best villains in any movie.
Now since all of that is perfectly fine just picture when you see a whole movie building up a showdown just to find out that the main character or Good Guy character was gunned down off camera by random Mexicans in a gunfight that they don't even show in the film.
It's honestly the worst thing I've ever seen happen to a movie. Talking over with friends they said it actually comes up often in lists such as biggest Wtf moments in movies and that it's the Coen brothers messing with the audience but I think it's much more than that. It seriously ruined this movie. I'm still giving it an 8 for it having my attention up to that point and the actors did amazing jobs. But from that scene on I seriously am not even engaged in the movie.
Am I alone on this one?