In my experience I've generally fucked things up precisely because my reaction was worse and inappropriate compared to what the partner did.
I think I am "lucky" in that my wife is amazing and I don't have to be on-guard again truly malicious and inappropriate behavior from her, so I have the "luxury" of focusing on controlling my own emotions and responses.
But then - WTF! How are people in relationships with people that you have to be so on-guard against?