Some of the things folks frequently advise for any event, etc where booze is (for you, was) a big part:
Plan your time in detail- activities, things to keep you occupied. Ex, if kids will be around, plan things focused on them.
Always have water bottles/nonalc bevs handy (I ALWAYS have a water bottle in my purse, in the car, multiple places, really- not to mention all the diet coke!) - and snacks - let sugar be your friend if you need to - I find that certain protein bars are actually tasty - I keep one in my server's apron at work so I don't go 8 or so hours without eating
Be the picture-taker, the organzier, the chauffeur, whatever keeps you busy and requires you to be focused and engaged
Do not isolate!!! Don't put yourself in a solo jaunt or a situation where you can sneak drinks or such
Have exit strategies - excuse yourself from an activity entirely, decide to take an early exit if you need to - claim you're tired and need a nap, ready for bed, WHATEVER
Check SR, call or text your sponsor if you're in AA, call a friend
If you can, have a sober partner in the group who you can lean on when you get the first inklings of being squirrelly.
Or, don't go.
Planning and being willing to execute your sober plan are the keys.
Good luck.