Head on impacts usually have the most effect on the front wheel, fork, and the top / downtube right near the head tube. On a folding bike, this would just be the "frame tube" before the head tube.
Here is an example. I was the rider of this bicycle when it was involved in a collision involving a driver weaving through a gap against right of way, and pulling out in front of me. The impact velocity was approximately 40kph.
In the photograph, you can see 4 things:
1. Wheel has gone out of round.
2. The fork no longer follows the angle of the steerer, it has been bent backwards towards the frame.
3. The downtube is no longer straight and has compacted inwards between the O and the C on the Rocky Mountain logo.
4. There is a split in the paint visible just before the headtube on the top tube of the frame. This split is where the frame bent on the top, following the trauma at the downtube.
When inspecting your frame for damage, pay attention to all of these things specifically. Take good care to look at the condition of the fork, observe it from all angles, check for paint damage around these areas which is indicative of the metal giving way.
Without seeing the bike, I could not say if it were safe to ride. I would advise taking it to a nearby shop, preferably the dealer you purchased it from, and have the bicycle inspected and appraised for damage.
It's good that you weren't hurt too badly, hopefully you can get a full recovery on the losses for your bike. I wasn't so lucky in this instance, and have a permanent knee injury.