Admittedly, I haven't read your entire post. I was too lazy for that. I still think I can give you some tips though.

First of all believing really helps with anything in dreams. I'm normally someone who doesn't believe something they haven't seen as well, but when there's a perfectly good explanation for something, then there's no reason to doubt it, is there? That's why you might want to read up on why lucid dreaming is definitly possible and is by no means a spiritual thing like for instance astral projection.

About the nightmares. there's not much you can do about them until you've learned to have lucid dreams, at which point you'll be able to confront them and put them out of your mind forever. The fact that you're thinking of them again might cause you to relive them in your dreams though. Horrible as that may sound, you can use it to your advantage by realizing that you're dreaming and confront your nightmares (might wanna read up on that too if you haven't)

It's best to start by learning to have DILDs, using reality checks and autosuggestion. WILDs, unless you're naturally skilled at inducing them (which I assume you're not), are harder to learn and it's therefore better to focus on them after you've gotten at least one dream induced lucid dream.

Finally, I recommend you read "Exploring the World of Lucid Dreamin" (EWLD) by Stephen LaBerge. This book is generally considered to be the "lucid dreaming bible". It's very interesting and contains everything about lucid dream, from their history to how to induce them to what to do with them and how and why we dream.

I hope you can use any of these tips and that you have a lucid dream soon. Good luck.