What does it mean that ripples are destroyed?
Nobody gets that fee, as simple as that.

To protect the XRP Ledger from being disrupted by spam and denial-of-service attacks, each transaction must destroy a small amount of XRP. This transaction cost is designed to increase along with the load on the network, making it very expensive to deliberately or inadvertently overload the network.
Every transaction must specify how much XRP to destroy to pay the transaction cost.

See the Ripple Developer Center for further details.