I think it is human nature to try to anticipate things. You see it as strange. I see it as mentally exploring alternatives in hope of finding the good answers ahead of time. The "stream of consciousness" sometimes becomes a "whirlpool of confused consciousness" so you have limited choices when that happens. Either ride it out or try to escape it. You come out of it or stop it only with one of a few possible situations.
First, if you have a VERY disciplined mind, you can direct your thoughts elsewhere. Try reading a book or watching a movie. Distract yourself. Oddly enough, distraction might clear your mind enough that when the distraction is over, you might come up with a solution more readily.
Second, if the anticipated conversation/event/threat occurs - and passes - then you can move on to the next crisis. In which case you begin to second-guess yourself as to how you handled that last problem. (Gets you coming and going... the mind is funny like that.)
Third, you might seek medical advice if you start to obsess over the threat - but spiritual advisors can perhaps help. If you go for medical advice, ask anyone who prescribes a drug why that drug? But if they suggest one of the calming herbal tea concoctions, that CAN help sometimes. I often enjoy a good jasmine tea or a chamomile variety as a calming agent.
Fourth, if you have a really good friend, tell that person you have a problem to discuss. Then take that person to lunch or dinner and talk over the problem. I can only guess why, but being forced to speak out loud about a problem often brings it to a different level inside of you and sometimes helps. Forcing your mind to organize your thoughts well enough to speak them might help you solve the problem. Do that only with a good friend. I don't know your personal preferences and religious beliefs, but another variant of that solution is to take that good friend out and talk your way through the problem while you get stinkin' drunk together.