Hello Anne, your father in law probably has tried to let you all know that he still around and that he is more than okay. I chuckled reading part of your letter, your father in law still sounds frisky.
Not every blinking light or encounter with an external energy force will be your father in law. You and your husband have lost other family members besides the father figure, so there is no way for me to know for sure who did what when. But you or the person who had the encounter will know better than anybody, by how you felt about the incident. Always trust your intuition of what the experience means to you at that time.
Your father in law and others will draw close in times of fear, stress and hardships. As well as in times of love and laughter and happy occasions. Regardless how your father in law feels about your husband's need to leave the marriage, he would not be judgmental about it and only want to help all involved.
You have to know that if your father in law or anyone in spirit wants another to know something, there is nothing that can prevent them from getting their message across to the intended recipient.
I wish you all the love and support to deal with your recent marital situation and I know that with time all will be well for you, please trust. Ask your father in law and all your loved ones in spirit to help you. But what if your marriage is over? That is a reality that may or may not be true. Grow and create who you are in regards to the hardships you are experiencing now.
I wish you all the best.
I am sure the resounding message would be : all will be okay.