it was my fault
Sei que a culpa foi minha, admito.
I know it was my fault, I admit it.
Você acha que a culpa foi minha?
Do you think it was my fault?
Devo admitir que a culpa foi minha.
I must admit that it was my fault.
Desculpe a confusão, a culpa foi minha.
Sorry for the confusion, it was my fault.