Is it possible to pull your groin from falling off your bike?
Also for the pain to come about a week later after the bruising is gone?

Yes it's possible, but maybe due to that area already being weak.
For example, I was operated in the groin area in 1997 and 2005.
That has left me very cautious as to how I stretch my groin area, whether I do strengthening exercises or not I have to be careful.

I would think it possible to pull or strain most anything falling from or crashing a bike. the pain coming much later might be something else. were you off the bike for that week?

it's possible to pull anything depending on the way you fall, and what you stretch. as for pain returning, that's pretty common, since the area might not be fully healed (even if you no longer feel pain) and then you re-injure it doing something small and insignificant. As an example, when I was 8 I fell out of a tree, damaging my hips (external rotation). Since then, almost every month I do damage to myself since they I never healed properly.

I didn't stop biking because I didn't feel anything was wrong. I had popped the spoke out of the hub so I couldn't ride for a day or so. Also the pain came back when I stepped out of the shower. The tub is one of those old style lifted up tubs so when I put my leg down on the ground I got a shooting searing pain. The pain prevented me from lifting a bended knee up fully and would be constant throughout doing that, bringing it up and setting it back down. I did take a break from biking as after the ride home from work the day the pain came back I was on the verge of tears the entire time. A week later, I believe, I ran 10miles on it without too much trouble aside from that being one of my longest runs in awhile. Now it's been intermittent pain and mostly when I am just sitting around for long periods of time. When I'm active, no problem. I'm seeing a doctor today, finally...hopefully it's not going to be a recommendation to stay off the bike or not run. /:

Thanks for the replies!