£100 billion out of approximately £13 trillion, yes. Remember if you are going to talk about the "EU economy", you're talking about the second biggest economic bloc in the world, surpassed only by the USA.
The simple truth is that the EU economy can afford to absorb the losses of a no deal Brexit, whereas the UK economy has about half of its entire trade affected. Once again, this goes back to the fundamental misconception that the UK is still a great power/empire, when it isn't.
Tusk's soundbite is just that. It's not especially reflected in the EU's actions, which seem to suggest that they want Brexit to go badly (for obvious reasons - if they grant us an amazing deal then there would be no point in anyone else being members).