Stressful upcoming things are brain gunk that you can dismiss, if that helps you at all. I don't mean that you don't have to pay your taxes, socialize with button-pushy relatives, or take a 17 hour flight. Maybe you do, but it's not happening right now. That's the key. If you're playing it out in your head for weeks ahead of time and suffering as a result, what you're doing is engaging in past/future storytelling. "Oh, no. This will happen. Oh, no. That always happens. Oh, no. What if some other thing happens?"
All that's required to end the pain from this is you taking a step back from the story the same way you do with binge urges. Look at what's real, what's actually happening around you right now. Maybe you're sitting on a sofa, looking out a window, hearing the kids play, whatever is going on. Is the pesky relative, stressful chore, or difficult conversation there right now? Only in your imagination, right? Like a binge urge. Your brain is firing off signals for you to embrace and debate, empower yourself with, struggle against, whatever. You can't stop the thoughts from coming. They're automatic, but how you meet those thoughts and what you do with them is totally up to you.
Ask yourself, "Am I ok right now? Is something terrible actually happening right now?" This works all the way through the stressful event. When you're getting dressed to go there, walking in, maybe sitting in a waiting room. Are you ok? Is something terrible happening this instant? Or is the sky still up there? There's wind in the trees. Your shoes are comfortable. There's gum in your purse. There's a man on a bicycle. If you can stay present through the whole thing, you'll be fine. The present is always ok. I do sometimes cheat though. If I'm going to let myself veer off into the land of imaginary future storytelling, I go over and over what it will be like AFTER the thing I'm dreading. I let myself experience it in detail. Oh, how relaxed I'll be, how relieved. The thing is behind me! I'm living today as if it's already behind me! It's almost like time travel. I focus on how I'll feel and what I'll look forward to when it's done, not on the dreaded thing itself.
If that helps. I also found a pretty cool anxiety cheat sheet a couple of weeks ago if you want 50 practical things to try.