That's why you need principles. Principles are those good friends that give you advice when you need to take action but your mind came to a standstill.
For instance, you might want to set the following principle: "cheating on my girlfriend is awful because loyalty is the most important thing within a relationship." Cheating is the ugliest deed. If your partner cheats on you, that's just a sign that he/she cannot control his/her impulses and that an impulse/temporary emotion is more IMPORTANT than your relationship. _______________________________________________
Thus, when you're drunk and want to go to a hot chick, you talk to your emotion and say: "be obedient." Hint: be sure to set principles that are based only on what you can control.