You have nothing to be worried about, mate. I am equal parts fascinated with air disasters and have massive flight anxiety, but flying is overwhelmingly safe. KLM, like most major airlines, is a great airline and very safe.
Your flight will go off without a hitch. It's saddening to hear about these tragedies, but you have to keep in perspective how many flights take off and land safely every day.
My advice is pop some xanax if you have it or have a few drinks at the terminal if it helps you relax, then just enjoy the flight and bring something to distract you if you can't sleep. I find talking to the passenger next to me, if they are receptive, also helps.