If the coins do remain unspent do they get returned?
May I?
No they won't, sent bitcoins are irreversible once the transaction was confirmed (
yours currently has 251 confirmations).
If you have posted earlier when you've just sent the txn, there may be a chance.
This is useful when you accidentally sent to the wrong address again:
Since you're using Electrum, I'd suggest you to upgrade to the latest version 4.0.4 from the
official site (
and verify the file's signature).
That version has an option to "
cancel (double-spend)" an
unconfirmed transaction if it's marked as rbf (
default: on).