Yes, the "sit quietly and be still" would apply to you as well. This is good advice for any type of situation, not just here on the boards. When people are struggling for answers to questions as to why, how, what if, etc., the best thing you can do is sit quietly and be still. You are trying too, too hard to find answers to questions that none of us can answer for we aer not in your xh's head or know what transpired in his young life. He may not even be able to answer some of the questions either.
Renee, sitting quietly and being still do not mean that you not move on. It means to allow things to fall into your lap naturally and stop struggling to find answers. Sometimes, when you least expect it, the answers will appear out of no where. By doing what I have advised, as well as others, you can move along and put your focus elsewhere.
Put this situation back in God's hands and you work on something that you do have control over...
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.