Impending Doom

Something that is common amongst trauma survivors is impending doom. I am struggling with it today. Because we have known so much ongoing trauma, it is hard to accept when good things happen. When life is going well and I am happy, it is very common for me to get a deep feeling that something is about to go wrong. Something big, like I am going to die.
Many years ago, while still in the depths of severe depression, I was dating. I had met a nice guy one day and a few days later flew interstate to spend time with family. The whole time I was away he was in contact with me saying how much he wanted to get to know me and missed me. I was feeling very accepted and wanted. When I got on the plane to come home, I was 100% sure we were going to die in a plane crash on the way home. Life was too incredibly good, so something bad had to be about to happen. I couldn't imagine life getting any better than it was at that time.
Since then life has improved immensely and so has my state of mind, but the fear of something bad happening when life gets good, is still with me. It is almost paralyzing and I just want to sit in a corner and hide until the bad thing comes. It tarnishes the good things that have been happening.
Imagine a child enjoying playing or being with friends, when the abuser comes along and insists the child  goes with them. The child gets abused. This sequence happens repeatedly and it doesn't take long for the child to learn that good times are always followed by bad things. Before long it is in-ground into their belief system. Don't get too happy or the bad things will come. At worst we may even die. It even makes me less inclined to have good times, because I don't want the bad stuff to come.
Ultimately I need to get used to good things happening, and accept that life will go on and in most cases good things can continue to happen. It is a big thing to relearn.