Hi Miss Lena,
I get the feeling that going to this picnic means a lot to you, and believe you will feel defeated if you allow the incident between you and this uncle to make you decide not to go. You are also upsetting yourself both by anticipating your meeting with this uncle and the comments you think your family might make about your blood sugars. In a way it's unfortunate that we human beings are able to anticipate a future event like this picnic, because 99% of the time our expectation is much worse than the event turns out to be. Imagine instead yourself coming home from the picnic saying to yourself, "I'm so glad I decided to go..., I really had a great time." Picture it... because I believe that's what's going to happen.
It's already Friday and the picnic is tomorrow but try to change your focus. Try to focus on those members of your family you can't wait to see and imagine the hugs, the laughter and the catching up you'll do with them. Also, try to see the positive side of YOU, because of your diabetes and because most of your family members love and care about you, possibly being the center of attention. If you maintain the attitude YOU expressed how "you just want to be you and have a good time," they will all say, "Hey, Lena looks great and she seems to be dealing with her diabetes very well." That will make you feel great. (Dress very nicely and look your best. It will go along way to boost your confidence too.)
Just one more thing, and that is that what I believe you SHOULD be preparing yourself for now is the food you are likely to eat at the picnic and perhaps the exercise if your family plays games like Frisbee or Volleyball. A picnic is a unique "eating" situation and you want to avoid going either high or low because THIS can surely ruin the experience. If you're a carb counter, look up the number of carbs in typical picnic foods like hamburgers, hot dogs, cold salads, snack foods (potato chips, pretzals, etc.). You can even plan in advance what you will eat, like one hamburger, one hot dog, etc and how much insulin you might need to take. BRING glucose tablets, just in case. Plan to test your blood sugar regularly like every hour or less and perhaps accept a little looser control like a sugar target between 150 and 200 even if you normally strive for a target closer to 100. This way you will feel well without risking a low blood sugar reaction.
To show you how funny events like this can sometimes become..., many times when I would test my blood sugar at a family gathering, many of my family members and friends would ask me to test theirs. So I would bring extra lancets and perhaps a spare meter so their "perfectly normal" blood sugars (i was so jealous of those lucky __________) wouldn't affect my pump averages. Perhaps you could even find out if this uncle of yours is "brave" enough to have his finger pricked!! Just have a great time, Lena, and don't eat too much. I iknow you will.