You seem to have forgotten the key issue. In those dark days we who believed in a non racial state could vote Progressive, the equivalent of today's DA.......... but there were only two real choices. 

One was the ANC whose avowed policy was to convert SA to an equivalent of Russia's Eastern European satellite states.
The other was the Nationalist Party and apartheid.

If I'd had to choose between the two I'd have voted for the Nats. The damage, wrongs under them were I believe far less that would have been the case had the country been handed to the ANC.
Fortunately communism collapsed and this enabled the move away from apartheid. 

If one looks at the mess the ANC is making - degraded currency, falling growth rates, sky high crime, rampant looting, the Guptas, wrecked education, whites cleaned out of now bankrupt SOE's and from anywhere else the government can exert influence, etc it's highly probable that with communism considered an option SA would have totally collapsed.