I know when you are with the kid or kids and A is off doing whatever they do, that it is especially hard. I would feel so trapped, and I would have these delusions of his granduer. Like he was out having a blast. That is simply not true. He is wrestling with demons, which does not require your pity, but, please try to put into perspective the fact that he is pursuing or toying with a girl who lives with her mom.
This alone indicates his poor judgement, his immaturity.
He is going to a person/circumstance that allows/condones his behavior, maybe enables or provides his alcohol. This is the crack house type of thing for alcoholics. They go where they can get fed their drug unobstructed and unquestioned. It is sad, really.
But it is not yours. You are able to be happy, you are not addicted and immature and pathetic. You are parenting, which is the most important thing we can do.
I am sorry for your pain and I understand it well.
I know it sounds silly, but when I was in pain like that, it would always feel like I didn't want to snap out of it. Music could shift my mood, but I wouldnt listen to it. A friend or family phone call could help...(if I discipplined myself out of obssessing and ranting about him him him.) It can help to ask how others are doing.
What do you love?
If you feel like you have been isolated from the things you love, and feel like there is no where for you to "go" with your own pursuits, I find writing is incredibly helpful.
Just let it flow out. any thought, any idea, any feeling. Then you can delte it, or keep it for posterity. Its also helpful to post here.
I hope the clouds lift soon. And they always do.