I made out with someone else and I have a boyfriend. I was drunk?

I feel so bad and guilty I really feel like he deserves to know. I’m scared to tell him because I’m worried he’ll think I’m some slag who can’t be trusted and break up with me which he would have every right to know. We have been together for 2-3 years and I love him so much. I was at a party with my girl friends and we all got so drunk. Long story short two of my girl friends started kissing and I laughed and looked at my mate. Then the other girls got involved and we were the only ones who hadn’t kissed another girl she said “fuck it” and leaned in and we started making out. I stopped and felt horrible I sobered up and left. I guess my excuse is I was drunk and she’s my mate and it was only as a laugh. But what should I do? Should I tell him? Would he break up with me?
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+1 y
I’m also straight so have never felt an attraction to her and never will
I made out with someone else and I have a boyfriend. I was drunk?
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