I'm going to tell my brother in law that my wife catfished me
Why do you want to tell your brother in law about your wife?
He need's to know he can't trust her.
Even though you are telling about your wife, it is acceptable to warn you brother in law about your cat-fishing wife. It is good to tell others about a distrustful person.
I don't know, I'm going to do it.
You should probably talk with your wife about why she lied, you might not like the answer but you should be able to handle it. Maybe only keep it in the family she is close to if you are worried about her.