Actually, this is not my first time revealing my identity to you.
actually = 実は
this is not my first time = 今回は初めてじゃない
revealing my identity = 正体を明かす
正体を明かすはまた違う文脈で「blow one's cover」として表現できます。しかし、これは正体をバラすと言う意味であります。例えば、泥棒は目撃者の目の前でマスクをとって、自分の正体を明かしました.
The thief blew his cover when he took off his mask in front of an eye witness.