At the end of the Apartheid it seems like the Afrikaners populations would have wanted their own state, after they had mistreated the africans for long time and where about to become a minority in the new country. Why was no effort made to split the country in two?
I have looked around for information on this but all I find is modern stuff about racists living in the middle of nowhere.
It helps to think of the end of Apartheid, as the conclusion of a military insurgency in Southern Africa.
It couldn't have been split into two because the independent Afrikaner country would have had to deal with an insurgency and hostile neighbouring Governments. Plus, outside of the context of the Cold War, they would have likely lacked international support.
Here is Mandela on the Angolan battle of Cuito Cuanavale:
The decisive defeat of the racist army in Cuito Cuanavale was a victory for all Africa. This victory in Cuito Cuanavale is what made it possible for Angola to enjoy peace, and establish its own sovereignty. The defeat of the racist army made it possible for the people of Namibia to achieve their independence. The decisive defeat of the aggressive apartheid forces destroyed the myth of the invincibility of the white oppressor.
The sole policy left to the Nationalist Party was the one taken.
Somewhat different take: this was, in fact, a demand of some hard-right Afrikaner nationalists. It went nowhere for two major reasons. First, it was ideologically unacceptable to the ANC and the broader anti-apartheid movement, which was premised on demands for majoritarian rule in the whole country, not the creation of a smaller white-supremacist state. Second, on the other political side, most National Party leaders were not interested in giving up claims to their real estate and to most of the country's productive economic assets (mines, railroads, etc), which is the only conceivable way that they could have even tried to negotiate such a split.
It's important to keep in mind that the National Party did, in fact, spend decades trying to split South Africa into multiple "countries," and to deny black South Africans citizenship rights by transferring their citizenship to these new "countries" (more commonly known as homelands or Bantustans). This strategy meant that any attempt to carve up South Africa had already been fundamentally discredited in the eyes of ANC negotiators, as well as the anti-apartheid movement more broadly.