I've never been to therapy or know of one near me@GeraS, what @ruborcoraxxx posted is absolutely correct - this sounds like a classic case for which cognitive behavioral therapy was developed. Have you ever done CBT? Do you have a therapist?
You could also check out the "bible" of CBT - "Feeling Good" by David Burns. There's even a brand new edition, just released, called "Feeling Great."
I will try i hope it can help me.Something that worked for me when I was afraid to die of several cancers at age 15 was to take distance from the thought and seeing myself having that thought. Then, telling myself that dying of 5 different kinds of cancer at 15 would be not only improbable, but extraordinary. Humor has helped as well.
Perhaps something you can try is to see yourself having these thoughts and tell yourself well, I’m having this catastrophizing thought again, and let it pass like something you do actually see (a leaf, a piece of paper, an advertisement, whatever you might prefer). Make a list of what makes it very improbable, so you have counter-toughts to battle the catastrophic ones in hand when they happen. Then eventually why not grounding yourself in the fact you do have loved ones and hone the positive aspect of the feeling and not in the loss.
So to resume
- taking distance from the feeling of the thought and observe it
- having reality checks all ready and running
- redirecting attention to positive feelings
It’s not perfect but it did help me tremendously also when I was deeply convinced that people covertly hated me, thought I was going to lose my eyesight or anything like that. It takes time, it’s part of obsessional modes of thinking but it’s possible to mitigate it when it becomes overwhelming.