"What happened yesterday was a nightmare," said the Belgian, who is racing in the DTM this year with SSR Performance.
"I know I’m smarter, I know you don’t take that amount of risk in a 24h race.
"It’s painful to be this open in public but the reason behind is that I was racing my brother. My emotions took over and my brain stopped working.
"We’ve been competing against each other since we were kids, never backing off and rather breaking a leg then [sic] loosing to each other.
"Unfortunately this competitiveness took the upper hand yesterday. I regret it badly, it was unprofessional.
"I have absolutely no hard feelings towards Dries. In the contrary, I’m a very proud brother. In the future we will have each others' back instead of fighting each other.
"Today was a black day in my career. I will regret it for a very long time but that’s how life works."