There appear to be two damaged components: the bearing housing, which Husqvarna calls "Housing, Mandrel", part number 532 18 72-81, and the deck, which they call "Mower Deck Assembly, 42"", part number 532 43 98-17. There seems to be some ground for suspecting that the design of that housing is not good, and this may have been a factor in the fracture. The fracture in turn caused the destruction of the deck when the blade hit the top of the grass discharge port. When you have the complete housing assembly removed, and we see some close-up pics of the fractures of the attachment points, and the condition of the deck around the housing's mounting holes, we can discuss this further.
For your own interest you may care to download the entire illustrated parts list for your mower, from here:
http://m.husqvarna.com/ddoc/HUSI/HUSI2012_AAaa/HUSI2012_AAaa__96041023601.pdf(It's free.)
There is something else I'd like to clear up. I have the impression from something you said, that the mower may have been running with a broken blade. If you did that, it would fatigue and break the bearing housing in exactly the manner it has been broken. It shouldn't happen, because there would be a very noticable vibration of the whole machine if it ran with a broken blade.
Please post pictures of the blade, whether broken or not.
Obviously if it ran with a broken blade, that constitutes abuse and would not be covered by warranty unless the blade itself was defective and that is why it broke.
