My son just cracked two ribs ( rugby , not riding )
The important thing is to cough whenever you need to, no matter how much it hurts, otherwise you can get a build up of mucus on the lungs, that can lead to plurisey ( spelt wrongly !) or pnuemonia.
The doctor told him this this the most important thing to remember.
Healing time is individual, he was in agony, but back playing after 3 weeks with no pain at all.