Here's my take on your predicament:

To Sell
-I doubt you can still sell it in this condition

Repair
- I thick the internal bracing beneath the bridge has come undone. The bracing is glued to the soundboard for reinforcement to resist torsion by bridge plate due to string tension. The bracing need to be re-bond to the soundboard with glue and allow it to cure for say 2 days. This sound simple but you need special sound hole clamps to the area during the curing stage. The epoxy which you applied on the soundboard do not help the cause of the problem. You can contact some of the repair experts for a quotation. If the cost exceed 50% of the price of your guitar, then you may as well buy a new one, unless you have a sentimental attachment to it.

Donate
- Give it a friend or someone who wish to learn. It does not seem heartless to me!

Final take
- If you choose to keep it, do change the strings to a lighter gauge!