<p>Most people have been drunk at some point in their lives. Only a fraction of that number would be low enough to sleep with their girlfriend’s friend, or the boyfriend of a good friend. Avoid this substandard and tiny fraction of the population. Alcohol does remove inhibitions to some extent, but we are still very much able to choose something big like this. You might flip someone off, or speak out of turn, but flirt and then have sex with someone on the forbidden list? We are humans, not animals. This is not a forgivable offense.</p>
<p>Consider yourself lucky. You learned early on, and you weren’t married. I sympathize with your pain, but I am confident you will (after some suffering) get over both the cheater and the non-friend (if you are smart enough to make a clean break from them and move on).</p>
<p>One more thing…You didn’t waste a minute on him. Every minute of your journey was for a reason, and it can all lead you to something better.</p>