For as long as i have known you, you have always been too hard on yourself. A lack of judgement due to alcohol consumption is something you would naturally regret, but you cannot let it consume you. She came on to you pretty hard, despite being in a relationship. Either she was extremely attracted to you, or was in a very emotional and possibly physically unsatisfying relationship. Those two things spell trouble for anyone involved. You are only human and a loss on control happens. Learn from it, move on. I would not avoid this individual. Do not seek her out, but do not go out of your way to avoid her either. If you see her, talk about what happened, else you will have awkward moments every single time you even so much as hear her name in passing. And that is no good for your mental state of being.