Nights suck a lot of the time, especially on the weekend if we are alone (even if we have the kids with us, we are alone in terms of not having an adult partner with us). We have time to process our thoughts and they can be terrible, confusing, and sad. You do need to process them, but you also need to do things to take your mind off them and be happy.
Yesterday my kids went to their dad's for the afternoon/to sleep over and I took time to write in my journal about my feelings about AX, but I also hung out with a friend at her pool, got healthy Chinese takeout dinner for myself, called my mother, took a bubble bath, and laughed a lot over a sitcom DVD I got from Netflix. Being alone with my thoughts can let them run away with me, so I balance my thoughts with happy things.
I know you feel resentful, hurt, and angry that your A left you holding the bag, abandoned the children, and left you hurting and without a partner. When my AX abandoned me and my kids twice last year, I couldn't even accept it at first. I cried on the phone with my mother: "HOW could he have DONE this to me and the kids?"
My mother said, "What do you mean, honey? People do this sort of thing ALL THE TIME. Don't try to make sense out of things that will never make sense. Just be grateful that you are not the type of person who could do this type of thing."
It IS stunning that someone could abandon his family without a backward glance. My AX tells me that he misses me and the children terribly and that he's in a tremendous amount of pain. I honestly don't care anymore. This is what he chose, and now I get to choose what I do with my life. And YOU do, too.
Process your thoughts, but don't let them run away with you. Give yourself reasons to laugh and feel good even though you're hurting right now. And remember, it's likely you won't be alone forever. But even if you are, it has to be better than the agony of life with someone who isn't there for you or could abandon you at a moment's notice, right?