Feeling so guilty

Very briefly I have been with my boyfriend for over 10 years, he recently moved back to the Uk after living abroad for 2 years. I supported him through his time abroad and have been loyal and faithful. I love him a great deal but we have been having a tough time since he has returned as as he has been very depressed and pushing me away, this has been very upsetting for me. I have asked if he wants to end the relationship, but he sais no, so am just trying to be as supportive as I can. There is loads more to talk about but we would be here all day.

Basically I went out this Saturday with an old friend and got very very drunk, I don’t quite remember how it happened but we kissed for a second on the lips, not a proper kiss at all, but am ashamed I got myself into a stupid situation. I am now feeling horrendously guilty. What should I do about this? Should I just try and forget the whole thing? My boyfriend will not be able to handle me telling him this as he gets very jealous at the minute and I fear I would lose him forever, not just as a partner but a friend as well.

Can anyone advise on what they would do? I can't stop beating myself up over this stupid incident. I had absolutley no intention of kissing anyone that evening and I don't understand my behaviour.