After more than a year of bitter arguing that included lawsuits and public feuds, PGA Tour is merging with Saudi-backed LIV Golf ... and a lot of the players are pissed!

The stunning announcement was made Tuesday morning, with the companies saying they'll form a new, yet-to-be-named organization -- news that some of the PGA Tour players say totally blindsided them.

Collin Morikawa, the 18th-ranked player in the world, clearly had no idea the merger was in the works, Tweeting ... "I love finding out morning news on Twitter"

Another pro, Wesley Bryan, expressed anger over the merger.

"Love finding out info on twitter. This is amazing. Y’all should be ashamed and have a lot of questions to answer."

Bryan fired off another message ... "I feel betrayed, and will not be able to trust anyone within the corporate structure of the PGA TOUR for a very long time"

Tuesday's announcement was especially shocking because of the disdain the organizations have had for one another since LIV launched.

Aside from just being a business dispute, a lot of Americans were against LIV because of its tie to the Saudi Arabian government. In fact, LIV Golf is backed by Saudi's Public Investment Fund (PIF), controlled by the Crown Prince. A majority of the 9/11 hijackers (15 of 19) were from the country.

Jay Monahan, Commissioner of the PGA Tour, once posed the question ... "Have you ever had to apologize for being a member of the PGA Tour?," in response to blowback on American golfers who took large checks from LIV.

Monahan was talking about several high-profile former PGA Tour players who bolted for LIV, including Phil Mickelson who reportedly received around $200 million to join the org. Dustin Johnson left too, reportedly getting $125 million. Brooks Koepka reportedly got $100 million.

Not all players took the big money ... Tiger Woods reportedly turned down a whopping $800 million offer, while Rory McIlroy reportedly said no to $500 million.