Boyfriend kissed someone else

Ummm so my boyfriend told me he kissed someone else last week, he was at this random girls house and was drunk and kissed her once(I think), but he left her house before anything else happened. He said he’s really sorry and won’t happen again and didn’t know what he was doing and he promised not to do it again and I forgave him because somehow I did and still care for him. Is that the right thing to do? I’m unsure how to react but he definitely lost my trust