Did I overreact? I punched my brother?

I found out my wife had been cheating on me with my brother... I confronted my wife about it and she started to cry. She admitted that she cheated. I'm now thinking what to do on her part. This happened about 3 days ago.

Yesterday I decided to confront my brother, he got really defensive and started to curse at me... He said it was my fault because I wasn't a good husband to her and that I didn't deserve her because I'm not a man enough... Next thing I know he starts pushing me. All the cursing and pushing just made me snap. I punched him in the face and knocked one of his teeth out.

As far as I know me and my wife had a good relationship, maybe too good to be true. I never hit her or anything.
I asked my wife why she did it she said because I was too perfect for her...
Did I overreact? I punched my brother?
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