You will have to find some way to remove the bullet, there are a number of bullet pullers available in mechanical and momentum styles. -> One grabs the bullet the other looks like a hollow hammer that holds the case and when you smash it down, it relies on the bullets own mass/momentum to continue its movement forward and out of the case.
SOMETHING THAT HAS NOT BEEN MENTIONED YET - Did you hear crunching when you seated the bullet? If its at all possible that you crushed the powder when you seated the bullet and compressed the brass, then the powder would not be suitable for re-use either. You should have heard the crunching if you did this, and its probably only likely that you did it, if you were using a recipe with high load density. But by crushing it, you may have changed its burning rate/properties, and that is generally a Bad, or very bad, thing. So throw out the powder if you heard crunching.
As for the brass, review all your loading procedures and ensure that the brass was not over length to start with. Then you should do as advised about and wear eye/ear protection just in case. And then you May or May Not have success by running it back through the full length sizer, which I would do without the decapping pin. But be warned, it may not fit into the die, it may be more prone to becomming a stuck case, and it may still be out of spec even if you get it through the full length sizer.