It’s common, people do whatever kind of rotten thing they do and then figure out all kinds of reasons why their wrong action is actually right action, just ask them!
I’m pretty sure a person is responsible for the action they take independent of the action of anyone else on this planet.
This reminds me of, Flip Wilson if you’re old enough to remember him. “The devil made me do it!”
“I did that because he did that and she did that and anyway it’s okay what I did because that person sucks and I got hurt and I had to teach them a lesson and blah, blah, blah…”
We all do this to an extent but some people go through their lives doing nothing wrong, as far as they know. This leads them nowhere.
Do you take responsibility for your shadow ?