Oh, I see that now. Thank you. I forgot to change my settings back. Do you know how long it can take?
can take as long as 3 days depending on your luck. the bitcoins will return to your wallet if the tx still doesn't get confirmed after 3 days.
though you can double spend the transaction after 24~ hours. but you'll have to import the private key of that address to a different wallet and create a new transaction from there.
Nothing prevent him from double spend them now, if he want to.
I thought it won't work because a most of the nodes still have the old transaction and will reject the new one as a double-spend transaction?
Yes you are correct about that nodes that already have the transaction in their memory pool will not accept the double spend.
You can still transmit a double spend any time you like.
As you say if the old transaction is in all possible nodes then will the new transaction not be accepted... if not rebroadcasterd then will they will eventually they be dropped.
Cheers
