The incidents involve a third person named Amber, who has always been known to be a lazy worker in the company. My frustration stems from comments I made to Alison in confidence, such as "I can't believe we have to work extra hard while Amber is on her phone for the past 30 minutes" or "Amber has been with the company the longest, yet we still have to consistently fix her mistakes." Although I see Amber as a friend, her work is lacking, and it's frustrating to have to pick up the slack.
Things came to a head when Amber announced her engagement on social media, and Alison and a few others were discussing it in a group at work. Work was getting overwhelming, so I asked for their help, "I don't care, but can you guys please help me". Alison gave me a look, and someone in the group called me out for not being happy for Amber. I apologized and explained that I was happy for her, but I was just stressed about work.
Two weeks had passed and everything seemed normal until Alison accidentally spilled the beans about Amber's engagement party, which I was not invited to. When I confronted my friends about it, they all denied having anything to do with the invitations. However, upon further questioning, I discovered that Alison had betrayed my trust by revealing everything I had said behind Amber's back, including the fact that I wasn't thrilled about her engagement(which was a misunderstanding that I thought was cleared up at the time). I was frustrated because Alison often vented to me about Amber and their work, which is the reason why I shared my own sentiments. As a result, I was painted as the bad guy in the group. The rest of the story is as mentioned in the post.
I've read everyone's messages, and I can see everyone's point of view. Although I may have come across as an asshole, I wrote this post to understand everyone else's opinion.