When I was going through one of the most unstable and unsafe periods of my life, I took up the habit of drinking tea. I didn't feel like I had any safe place to store the tea, I always worried about other people breaking my cups, and I worried about being out in the open and making noise every time I microwaved the water. But. Every time I made tea it was like I could steal away from all the constant terror around me for just a moment.
I never really felt completely calm while drinking tea, but it gave me something where I could focus on the smell, on temperature, on taste. It slowed me down. Through practice it became a ritualistic thing and it's like my brain started associating tea with calm(-er than usual). Eventually when I made a cup of tea, just the muscle memory of going through the process would trigger a kind of comfort. It's not a permanent solution, but through practice it can provide some relief while you work things out.
If you have the ability to do so, I've heard that some people get a similar experience from baking cakes or taking showers. I would imagine that anything that engages your senses would work . It doesn't have to be tea.