it’s not your job to entertain him by sending him nudes
it’s not your job to satisfy him sexually because he’s horny
you are not required to do anything that makes you feel uncomfortable or that you don’t want to do
don’t be scared of “losing him”
he most likely wasn’t anything worth keeping
Girls need to be taught this from such an early age.
a boner is not a medical condition. you are under no obligation to do anything.