You say that you are not sure how you will cope. Why not? This is in your control. You get to choose how you are going to cope. Picture what is going to happen in your mind first, sorta like a dry run.
Make a plan. Anticipate someone offering you a glass of wine, how you will feel, what you are going to do about it. Will you make sure that you will have something in your hand to sip? Will you say to the offer, No thanks, I already have one going? Will you be able to step outside for a minute for a breather if you get panicky? Will you be able to leave when you want to?
Life is full of temptation, but we trust in our common sense and maturity to make the correct decisions. Temptations are manifest by urges or thoughts - but we are not our thoughts. We are so much more than one thought or urge.
I refused to be held prisoner by alcohol while I was drinking, and I refused to be held prisoner while I was sober too. If you go to your event, be calm, serene and confident. You will do this, and you will be so danged proud of yourself afterwards.