How to stop anxiety?

I seriously have been doing well and better since my fall out with a friend. But they’ve since been active in a shared group chat on Instagram when they’re not usually active on there. And reading back the conversation I just feel my heart race and my anxiety coming in tenfold :/ it’s super frustrating as I finally feel like I’m back on my feet. I don’t want to block them however as they’re the one that ended the friendship, not me. I still want to leave my door open in case they ever wanna reach out again.

Basically, how do I stop my anxiety being triggered whenever I see things related to them. It doesn’t feel like completely blocking it out will help as it’s like… I forget about them until I remember them again and it all goes to shit.