Was my wife wrong to defend herself against a pregnant girl?

My wife is 21 and before we got married 2 years ago she ditched most of her friends because she said they started doing nothing but partying and drugs so she didnt want to be around them anymore. Anyway, recently an ex friend of hers who is pregnant was calling her phone acting crazy and saying she was going to come to our house and kill her all because of heresay that my wife wasnt even involved in. So the girl showed up at our place with 3 of her friends and 2 guys, Im assuming to fight me so I go outside and just tell her to get off our property and she doesnt listen so my wife comes outside and tells her cops will be involved if she doesnt leave and the girl just throws a punch so my wife grabs her and punches her until the girl loses her balance and hit her an additional couple times before she leaves. Cops showed up afterwards and the whole thing was taken to court and my wife won since the girl was the aggressor and trespassed and was the first to assault. So was my wife right in hitting her back?