Reflect on this. If you have had this recurring dream for 20 years, then you know in fine detail exactly what happens and when. If things escalate and are driving toward the expected conclusion, change something. Do something different and change the story line.
Do you believe in free will? If so, then you have a choice to change things. It doesn't have to be the way it is in your dreams. But you need to snap the fuck out of it because the human mind IS a powerful thing and you may just draw what it is you fear most. Self-fulfilling prophecy where you subconsciouly do things that will bring you to what you believe is supposed to happen.
If you don't believe in free will, then why worry since everything is predetermined anyway and you can't change anything. Enjoy the ride.
Google quantum immortality for an idea of how vast free will actually is.
Finally, dreams are generally metaphoric in nature. They are rarely literal. They are a way for the brain to identify a need or a fear that you can't deal with consciouly. You have something that is unresolved, or a need that has been unmet and this dream is your way of dealing with it and reminding you of it. Sounds like you have a deep deep fear of death. We all have an instinctual (and natural) fear of it, but many of us have an irrational fear of it. Read Thich Nhat Hanh (Buddhist philospher) on the topic of death. It will give you another perspective and might make death a little less scary.
I'm not messing with you. If you feel like talking about it more, feel free to PM me. I'd be happy to hear you out.