Did my bf make a drunk mistake ?

My bf and I have been together for almost a year and a half. His is my first love and my best friend... last night he told me that on new years he got super drunk and this girl gave him oral (for less than a a couple mins) until he pushed her off. I’m so lost on whether to leave him due to me not being big on second chances with cheating or forgive him and try to make our relationship work... Please help me!

extra detail:

this is the first time something like this has happened

he’s a really good guy and treats me great other than this time on new years