No, bitcoins do not get "resent" back to the sender. What happens is that most of the network forgets your transaction (and that has already happened) and you tell your wallet to forget the transaction so that it reverts to a state where that transaction was never made. However, because you are sending from this wallet, it will not forget the transaction unless you tell it to do so, and you do that by using "Abandon transaction". Even though your wallet and the network has "forgotten" the transaction, it still has potential to be confirmed since someone else may still have a copy of it and may still rebroadcast it. Thus, to prevent that from happening, you need to spend the Bitcoin again to make a conflicting transaction that has a higher transaction fee that gets confirmed. You can just send the Bitcoin back to yourself. That will invalidate the original transaction.