"Minha culpa" is the coorect form. The other is unusual, but correct too. Se it: "Eu quebrei a janela, A CULPA É MINHA". "I Broke the window, its mine fault. " To a person who talk portuguese is strange heard " culpa minha" except in rare excessions that we dont ned see here. Well, I've a comunity about portuguese if you want subscribe yourselve. We would talk much more than this and i wish help you to improve this important language.

Both are correct, it just depends on how you use it, like: "a culpa é minha" (present) "foi minha culpa" (past)

ambos podem estar corretos, mas "minha culpa" é muito mais usado do que "culpa minha" both can be right, but "minha culpa" is so much more used than "culpa minha"

don´t worry mônica..both are correct; for example: ´´o prato quebrou, culpa minha, deixei cair.`` or ´´o prato quebrou, minha culpa, deixei cair´´ [´´the plate is broken , it is my fault,i did fall it.´´]. boa sorte!!!

depends... "a culpa é minha" when you do something not right or "minha culpa"when you say somtething "by minha culpa" in something religious...maibe