Hello
Even though I have filed for divorced 3 years after a long marriage to a narcissist , controlling, manipulative ,old fashion mentality and I needed to think before I speak to him just in case he will yell at me . Why I still feel sorry for him.? He will ended up alone when God decides to take him. I have not seen or talked to him since I filed the divorce 3 years ago. I got divorced when I was 60 years old I am alone but I do not feel alone and my life after divorce is more peaceful.

After he treated me with no respect by having an emotional affair with someone I know, and he have the gut to say nothing happened ,he threatened me, he was no fun to be around, he was unkind to people even to his Father ( God rest his soul)

I do not want To think about him anymore, this thoughts comes and go and I do not regret the divorce either.

Why at times I feel this way ?

I have a busy schedule and i also have friends that I can talk too.

Because your a good person that thinks about the future and how it will play out even for someone that you once loved. But he broke your vows and didn't treat you like the treasure he should have. Talk to friends, go take some classes, do things for you. You did the right thing Noone gets married and plans to be treated like a you described.
Women should be a partner in a marriage God made us from Adam's rib to walk beside.
Hope you find happiness and peace sounds like you went down a very rough road for along time and being with someone becomes a routine even if that person is not a loving good person.
Do something special for yourself look forward not behind. Hope this helps alittle.