I got fucked by two colleagues at the same time. Should I tell my bf?

Anonymous
So, two years ago I stated working at the office I still work at today. I was the youngest one at my office and really felt like "the new one", and like I didn't get taken seriously. On top of that I noticed that a lot of guys at work were sexually interested in me. One time I went drinking with some colleagues after my second work week, it got a little out of hand, and I ended up having a threesome with two guys. It was stupid but I felt insecure, didn't feel like I mattered aside from being the pretty one at work, and thought I could handle the booze better. Of course at work, word went around and my friends know it.

The problem is, I have a boyfriend now for almost a year and it's going well. I told him about all my exes and even the guys I fucked casually (not that many, if it matters). Except for that threesome. I don't know why but I feel like that's something he would be a lot more angry about. Should I tell him or not? I feel like I either should have told him immediately, or keep it a secret. I didn't dare to tell him at first since he met one of those guys and said he didn't like him. What would you advise me to do?
Updates:
+1 y
To be clear: I didn't cheat. The threesome happened two years ago, I'm only with my boyfriend for less than a year. It's clearly in the description. But thanks for the comments so far. I Still don't have an idea with the very mixed answers though...
I got fucked by two colleagues at the same time. Should I tell my bf?
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