Mason,
I have actually been there. yes I even wrote letters to my children. Why? What caused it? The realization that I had wasted 20 years of my life in a loveless marriage (I loved her, she never loved me - I was an escape).
There are many causes. I dont have an answer for that. I do know when I did. And as I wrote earlier, my sister pulled me back. I owe her.
Now I have a loving wife, a loving family, and pretty good health! And I dont think of it any more. I guess when we think there is nothing else, we think of that. We need to only be reminded that we do have something else to know that is not the way.
I am very thankful I have so many family and friends who do that for me.
I am very thankful this year, and this was a great way to say it. I Hope you know you are wanted and loved as well.
Peace on earth, and goodwill to you!