I am sorry you drank, you need to stay of that if you want to find out what you want.
I agree with Midnightblue I would not rush to any decisions.
Whether it was a man or woman you had the encounter with is not important, but you need to look into your feelings towards your girlfriend – you need to be fair there.
There is no happiness in unfair relationships.
Some have sexual feelings towards booth sexes – that is not important.
But it is important to respect those you love.