You have a few options, but none of them are particularly great.

• It's unlikely, in my opinion, that you'll have much luck in getting insurance to pay for any of the repairs needed. These were all pre-existing things that were there before you bought the house. Nor do I think you'll get too far with the home warranty paying for stuff. It's worth asking, but I wouldn't think you'll get too far.
• You can try to re-sell as-is. You will likely take a loss here. If the damage is that extensive, I have a hard time believing you'll get any fair price for the home. Unless you got the house FAR below market value, you won't be able to re-sell for what you paid.
• You can spend the money to make the repairs to really make the house sellable. This will cost you a good amount of money, based on your description. This may or may not raise the expected sale price enough to offset the repairs.
• You can keep the house, and hire somebody to make the necessary repairs, and then live in the house.

Personally, I'd just accept the loss, try to relist the house, and get out from it. Your GF hates it. Doesn't sound like you really wanted the house. You made an impulse purchase based on the prodding of your brother. Learn from this, and don't repeat the mistake.