You can use either divorce or separate depending on the situation. Divorce means that the once-married couple is no longer together legally (they've signed legal papers ending the marriage, etc). A married couple is separated if they are no longer together but are still legally married (for example, they're not living together but they haven't signed the legal papers). Usually couples agree to separate while they are in the process of getting a divorce. Hope this helps :)

you can say divorce! It's perfect

If they're officially not married anymore then they're devorced, if they're considering divorce but they're still married then they're separated. Devided is wrong.

Divorce is used when the people were married and then went through the official and legislative separation of the marriage by the state law whereas there's a saying "to go separate ways" if the people decide to be apart and no state power is present for that :)

Es divorcio solo si en el registro civil hacen el trámite de divorcio vincular. Si no se hace, pueden estar viviendo separadas pero aun seguir casadas legalmente y todos los bienes gananciales seran de ambos, ejemplo auto sera de ambos aunque esten separados, por que siguen casados ante la ley.