My wife does/did this to me. Been married 16 years. When arguing she cuts me off mid sentence assuming she knew what I was about to say, which her assumption was almost always wrong. She always got her 5 minutes in to clearly state her opinion every time. Anytime she would allow me to state my case she always came back how she felt the same way I did or felt it worse. She always had to win. I was always made to be the one who just didn't get it.
I try to pick my fights wisely. I don't need to win every time. I could let it go sometimes, others we both dug our heels in for the long battle of words which almost always ended up in a list of past grievances to show who had it worse. In this scenario nobody was the winner.
I didn't realize it but it was slowly killing my love for her. Each time it happened I reacted more emotionally charged than before. Because I love her, her words had meaning to me. I allowed them to reach me to the core. If anyone else said the words she said to me I would have laughed it off because I do not give them influence over my life. But she is my love, her words matter. This year, after 16 years of marriage, it came to a head. Each critique, passive insult made my chest heavy and numb. She was killing my love for her. "I should be a bigger man" I thought to myself "I shouldn't allow her to affect me like that." Well everyone has their breaking point. It took 16+ years for me to reach mine.
This is already a wall of text, so in short I did something that hurt her to her core, an ultimate betrayal. I didn't do it to hurt her. I did it because it gave me some sort of esteem.
Our marriage nearly derailed for the first time ever. We both had to own up to our short comings. At first she was offended I wanted to confront the way she talked to me when what I did was so much "worse". But this wasn't a contest. The fact was if she didn't change too the marraige was over. It was already on marching to its doom. We were just experiencing the symptoms.
We are now working on it harder than ever. And we both aren't perfect. But we both are still in love. I don't want anyone else.
TL;DR if someone loves you then please understand your words have tremendous meaning and impact, and thus expensive. Spend them wisely.