Cut it off, as others suggested. It's never going to be palatable.

To prevent it from happening, you might consider trying to double bag
(or vacuum seal, if you have a lot of zeal). When I buy bulk chicken
breasts, I put two breasts in a ziploc sandwich bag, press to squeeze
the air out. Put all of the sandwich bags into a ziploc freezer bag,
then squeeze the air out of that before sealing and freezing. They go
through several months just fine.

June