When you can't fully let go of the past

[Der/die AtheistIn]

If ifs and butts were candy and nuts, we'd all have a party.

Humans change, over time, for good or bad and in both directions. Don't drive yourself nuts over what could have been, because that is in the past.

The future in what you personally decide to do, is up to you. It isn't an issue of revenge or never forgive, or always forgive. 

Again, you keep asking general questions about a life we are not personally connected to face to face. There is no magic solution, no perfect answer.

I can only give you general advice, be it about friends, co workers or family. You can certainly have loved ones family and friends piss you off, and not disown them long term. But in general, it is unhealthy to stay in a long term abusive relationship regardless if it is family, co worker or friend. Ultimately only you can decide what you are willing to tolerate or not. 

My late mother and I were polar opposites as far as living habits and political and religious leanings. We certainly came to butt heads more on the living arrangements when we did live together. But it never got to the point where I thought she was Hitler out to gas me and stick me in the oven.

But even with just friends and co workers. They do not value you if all they do is verbally attack you on a daily basis to make you feel small or to get you to bend to their wishes 100% of the time. But getting yelled at by those who do value you on an occasional basis because they are having a bad day, that is normal. It should not be regular no, but conflict is normal, even among those you do get along with.

COMMUNICATION is the key in any healthy relationship.

How you have disagreements does not mean you should never have disagreements. It only becomes abuse when it is repeated verbal abuse on a daily basis and especially if it is physical. 

Everyone has a bad day and can occasionally  say things they regret. But nobody has the right to expect you to be a doormat.

Thank you for your answer, it was informative. But my question was about if someone feels sadness even after the abuse has stopped and the victim trusts the former abuser. The victim wants to move forward, but still feels pain from what happened in the past.
You know the saying: "forgive but not forget"? In my opinion, it's a subtle way of saying: " I fully trust you that you that you learned your lesson, but I can't forgive you, at least not entirely". Because forgiveness is when you stop being angry at someone who has wronged you.