A lot of people have used lucid dreams to combat nightmares. Instead of stopping them, which seems to be the extreme solution. Lucid dreams are not your problem, bad dreams are your problem. If you train yourself to control yourself within the dream then you can make the bad stuff go away quite easily. Have a look at this DV Academy class on Dream Control and Stabilization. I, personally, don't know how to stop lucid dreaming. I guess to stop paying attention to them would be my best guess, but I really don't know, because I try so hard to achieve lucidity.

I hope you find a solution to your problem. Good luck!