I find having lots of people around me can trigger my anxiety in certain situations too, my home is my sanctuary from that luckily. Can you have a relaxing bath? Or listen to something with your headphones on? I find that helps me get into my own little bubble, away from whatever else is going on.
Ah yes, the infamous overwealming feeling that comes with anxiety. I have had mini anxiety attacks when being in a house full of people, not so much with just family home, but I can understand how it would feel. We all need an "Escape", as Janey said above, can you maybe take a bath or music even? Some relaxing music?... I love the sound of water trickling down something so I want to get one of those mini fountains to ease my anxiety when I get it. I find they calm me heaps, maybe something to consider.
