You're developing a phobia, an anxiety problem. If you can't beat it and it's interfering with your life, therapy is the way to start in trying to get over it. If it's not interfering that much with your life, you work on learning the facts and you work on living your life until your brain learns not to obsess over this. But when we can't do this ourselves, that's what a good therapist can help with. It's like any other phobia, like fear of flying -- you have to learn how to not let the irrational take over from the rational. It can be hard and takes work, but hopefully you can work on it and get over it.