My biggest regret is that I did not stand up to my bullying stepfather when I was young. He was a truly dreadful man, who knocked Mum about too, and as I have only recently discovered, much worse to my siblings. I was absolutely terrified of him.
To cut a long story short:
I finally stood up to him when I was in my thirties, having not seen him for several years.
He tried to bully me again, shouting at me and poking his finger into my chest.
I completely flipped.
All the anger that had built up, suddenly came to the surface.
I screamed back at him at the top of my voice, I used swear words that I would never have dreamed of using, and yes, I poked him back in the chest too, and hard.
I could not believe his reaction. He stepped away from me. At last, the bully was getting a taste of his own medicine.
He threatened to call the Police.
Without mentioning the expletives that I used, I told him to do so.
Guess what, he didn't.
I never had any more problems with him after that.