my serama is injured!!!??

[Billys chickens]

i have a little serama golden hen she got into my pen with my rir rooster and he is very big his foot is half the bird and he tried to mount the bird but he is just way to big he got her cornered and kept pecking and puling at her head she has no feathers on the head or neck and is bleeding also on her back and on the sides infront of her wings are gashes that go all the way to the flesh and are bleeding what do you think i should do??