I'm shrinking

I'm shrinking.
I can feel myself doing it. Not on a physical level, but a mental one.
Part of it is next weekend. I'm scared, I'm anxious, I'm freaking out, but I promised to go, so I'm just bottling it up and compacting it and compartmentalising it, until it's this brick of negativity in the back of my head. I'm stuck in another country with people who care about me, but don't know me. People who miss me, and so I feel like the biggest bitch ever, because I'm dreading being trapped with them for a weekend.
What's scaring me? The plane. The travel. Being in an apartment with my dad, my sister, my cousin and his girlfriend. A day with no plans but to spend time together - God, how I hate that phrase. Then more time together. Then a meal together, where someone, usually my dad, will invariably make a comment about how much I eat. Then another day of time spent together. Then a plane home.
But I promised to go. My airfare is paid for, it's Granddad's 80th birthday, I have to go.
So I shrink. I turn it all inwards, and panic silently, so that no one sees it.

At home, I can feel myself doing it.
It's like she needs all the oxygen in the room, all the time, and so I shrink so that I take up as little as possible. I feel as though my time is not my own, because it is eaten up by appointments and meetings and everything else. Sometimes, I feel as though I am not mine.
So I shrink, to keep as much of myself mine as possible.

We have more stuff to get through this week. Parents evening, a vet appointment. I have to pack, she has to pack, we have to be ready.
I should be looking forward to next weekend, looking forward to the break. But I'm not, I'm just ... So caught up in my head that I can't think straight. I'm worrying, because me not being home means that she has to manage everything here. I know, realistically, when I can think that way, that things will likely be fine. But that quiet voice in the back of my head keeps asking, but what if it's not?
I don't want to say any of it out loud, because I don't want to project my fears, make them real. I don't want to make her worry about it more than she already is. I don't want her worrying about me more than she already it. I hate worrying people. I hate it.
They worry because I am anxious, and them worrying makes me anxious.
It's a vicious cycle.
So I try to shrink, hide it and keep it in that brick, so that no one worries.
But I worry, so I shrink, and I shrink because I worry.
I'm stuck.