Accident in Namibia, SH Ventus 2cxm

I was the PIC in the accident involving a Nimbus 4DM in Bitterwasser.
We loose the control of the glider at 3500 meters height and at 110km/h when we wanted to exit a poor left circling thermal.
Why?? I never use the airbrakes. I put the flaps in full negative position and after several spins I tried to stop the dive at very high speed, the two outside wings broke..
We succeed to bail out (less then 15 seconds with the parachute open for me before to reach the ground!)
We spent the afertnoon and the night before the rescue team from Pokweni found us early in the morning.
We wife and me are safe, just spin problems for me.
But I don't know what happends (no water or fuel in the wings).
I hope the investigations will found the reason of this loose of control in a normal flight condition.