Welcome, Purplemelon44! I'm going through the aftermath of a divorce myself . My marriage was 33 years long. While I haven't had the exact physical reactions you have, I did have said what my therapist said was my first panic attack: I thought I was having a heart attack--which sounds pretty simple compared to what you're going through. The part that helped me was having a smart family doctor and smart therapist. My hope for you is that you have (or find) two talented individuals in these roles. If it's a panic attack, yes, it can change and dissipate. But it sure feels like it never will!
I wish for the best for you. There's lots of wisdom in these forums. I know they'll help you too.