Hon, you are going to face this every holiday season. Especially as a newly diagnosed diabetic. It takes a while for it to sink in. But that being said, you aren't never to have any treat. It's just that you can't go face down into the box of cookies. The thing about diabetes is moderation. MDI and dose calculation allow you a certain amount of freedom to enjoy a christmas cookie or some other treat. You just have to estimate (or weigh the item) and figure out what you need to give to cover the treat. Don't go crazy and graze the dessert table.
Forgive the others for not realizing that you can't have all of the things they bring you. They are trying to be thoughtful in a non-pancreatically challenged way. We are pretty much odd man out at the buffet. When I started working at my current job, when we had office functions, I wouldn't be able to dive into the cake. I asked the administrator if it might be possible to get something besides a sweet thing. Next time there was a veg and cut fruit platter with some nice cheeses.
Why? Clincally: you have to deal with an insulin deficiency in your body caused by your immune system killing off beta cells which it things are foreign. Without treatment, you will suffer high glucose levels leading to weakening of blood vessels in the eyes and kidneys. If you don't deal with this disease in a responsible manner, you will feel rotten all the time, your eyes will fail and you will require kidney dialysis by the time you're 35. And with arterial schlorosis, you stand a risk of neuropathy (painful hands, legs and feet). From a reality stand point: it happened. Your genes have got certain switches that are not operating just right. I realize you didn't apply for this job but you got it anyway. There's no retirement, the benefits suck and no dental insurance. But you want to live and enjoy the most comfortable life you can. That requires we count our carbs, we figure our dose and we try to avoid as much unnecessary carbohydrate as possible. Management isn't a constant chorus of "no you can't" -- it's about how plan things. This is why diabetes management is self-directed treatment for the most part. Our doctors and educators give us the raw materials we need to do the job. We take that education and we apply it to our individual situations.
Holidays are something you will still have to deal with. They aren't placed on the calendar to vex you, but we as diabetics need to work out a strategy. If there's something you seem to not be able to resist, maybe you can share with someone else. At dinner and folks order dessert, suggest a couple of different desserts and enough spoons for everyone. You can have a bit of each and it won't send you into the 500s.
You can do this. Just try to let go of the emotional angst that is surrounding this. We sometimes feed the beast unnecessarily. Take a breath and a step back. The frosted cookie is the shark, the insulin is your protective cage. You can enjoy swimming with the sharks, but they can't hurt you in your protective cage. Carbs are kind of like sharks. They aren't all dangerous.
This kind of thing takes a little practice. Each year the service I use to file documents with the courts gives me a box of See's Candy (Nuts and Chews). It's on my desk for everyone to enjoy. Even me. When I really think about it, one piece a few hours apart isn't going to upset the apple cart.
If you ingest, test. Correct if necessary. Repeat as often as you need to.
If you can't discipline yourself to moderate your intake, it's best to leave well enough alone. But if you can be moderate, this isn't meant to be a punishment.