but i deleted bitcoin core mempool.dat?
what does zapwallettxes do?
It seems that it needs to put -zapwallettxes under the bitcoin-qt shortcut to make it work and it's a solution for stuck transaction.
I don't know if it will work but worth trying.
There are two options on achow's blog that you can follow how to use this -zapwallettxes and abandontransaction
You can read it from here
https://achow101.com/2016/07/Bitcoin-Core-Troubleshooting