I've flown a lot and with and without family. Do you know from where your fear begins?
I'll be honest, I've been on 3 ER landings and yes it was scary but one thing I know is that the pilots want to land safely just as much as I do and I know they do everything in their power to make that happen. I also know realistically that flying is safer than driving with all the crazies in the roads. I'm worse as a passenger in a car than a plane!!!
If your children pick up on your fear, then they will be fearful. Make it an adventure!! Don't let them know you are scared.
It's ok to be scared too, just don't go overboard. Watch the flight attendants, everything is routine so that should help you chill out. When I hear the ding at 10,000 ft I am just fine throughout the rest of the trip. I'm only white knuckles until that ding.
Go have fun... If needed have a cocktail or to to relax you a bit. Enjoy the excitement in your children's faces!!
Good luck.