Okay, thank you so much for the help! I've never had a transaction taking this long to confirm with the highest fee, so I got a little worried. 
The problem is that there's two transactions in the double spend, one with a high fee, and the other with a low fee. Unfortunately most nodes and block explorers can only see the one with the low fee. Luckily the viabtc transaction accelerator can only see the low fee transaction. That means if you can get it to accept it the viabtc mining pool will confirm it in the next block it mines.
The viabtc accelerator only accepts 100 transactions an hour and it's overloaded. If you submit your transaction ID to it exactly on the hour it might accept it. I just tried but I was too late, all the available slots had been taken a few seconds after the hour.
Try submitting this transaction ID to it on the hour 3eb102f7273c983e0fd52567da7ca41e3ef66a232f7d611ce563989376d78115
This is the link to the accelerator.
https://www.viabtc.com/tools/txaccelerator/
Maybe someone else can suggest a better solution. I'm not very experienced at using core.