Will:
It did not occur to me that the Dark Night is a period of rumination but now that I think about it I totally agree. Most of the time the fear is about the future, whether or not I have been a good person, am going to hell, am going to come back as a spider monkey, i.e. pretty useless but nevertheless frightening thoughts.
You can resolve those thoughts by asking yourself a simple questions. Can you trust yourself? If you answer "no", then those doubts are why you believe you need to hold on to your fear. At our core, we are all "good" - the things that cause us to be malicious or sad or angry are aquired traits we use to protect ourselves. If you trust yourself and allow your actions to come from spontenaity, you can see in real time that these "feeling" reminders aren't needed. It brings relief to take your trust away from anxiety and put it onto the spontaneous core of your intellect.
If you ask yourself, "have I been a good person?" Resond with, "will this question help me be good in the future?" Someone who is tense and anxious is likely to take out their feelings on other people. Instead, by being relaxed, you will be likely to be kind and generous. You don't need to be anxious about your morality because it doesn't help you be more moral. You are perfectly capable of pondering the merits of any action without fear of those actions, and without fear, you can more easily decide what will lead to your goal - being a good person.
If you ask yourself, "am I going to hell?" You can respond with, "does asking this keep me out of hell?" This question will just make you anxious, and that anxiety may cause you to do things you don't want to. There's no need to be afraid of hell if you're a good person, and the easiest way to be a good person is to be content and relaxed. There is no purpose for the anxiety you feel, so you can safely drop it, walk away from it, see it as useless. When you think about hell, consider the best attitude that will keep you out of it. By feeling contentment, you will not do anything that will lead you to hell. Thus, feeling contentment becomes the goal.
The best way to be content, is to trust yourself and trust the ultimate benevolence of spontenaity. Trust the core of who you are - a happy and harmless human being.
As for being a spider monkey, their lives don't seem so bad, eh? Haha