Is that considered cheating? Please answer

My boyfriend admitted to me that he got drunk and was dared to kiss some girl on the neck. We have been together for a year and some months now. And he is the sweetest person Ik. However, I’m confuse. I told him that I needed time to think. But I’m confuse if it’s cheating. I’m not okay with it. But he did come “clean” about it. I also told him I’m not mad. Which is the truth. I’m just confuse. Because a lot of things could be classified as cheating. So my question is if this was you…would it classified as cheating?