feeling hopeless

has anyone ever got over the rumination over eternity? I feel like no matter what I tell myself to calm down, the fear is still in the back of mind. I don’t want to be afraid of this anymore, but I had a flare up a few days ago and it feels like it’s never going to go away. The fear of letting go is what’s holding me back and I don’t know how to reason with myself that it’ll all be okay.