Do you still want to go to Brazil? If not, you can cancel the trip and get a full refund. If you still want to go, you may also want to check current prices to see whether you can get it at same price or cheaper by booking with someone else now (if which case, cancel and rebook separately).
The problem with flying back to WAW on the 24th is that AZ have no flight to WAW on that day, so you end up with a mismatch between GIG-FCO cancellations and FCO-WAW cancellations, leading to a forced longer stay in FCO. You should be able to claim back the cost of your hotel in FCO under Reg 261/2004, though, if AZ are not themselves willing to arrange the hotel.
Forget about travel insurance if you had not already purchased it: quite understandably, they won't cover anything that is known prior to purchasing the insurance and attempting to claim in such a situation is likely to be constitutive of fraud.