I think it is gone forever if you did it wrong! because you can't trace which people of that address you wrongly sent.
When it is happen just consider it as a donation or just give-up and learn from mistake, just double check first transaction before sending it.
I am just having hope that it will probably reverse itself since both coins are using the same blockchain. I am just giving it a period of one week and if it doesn't reverse then I will consider it as gone forever or unintended donation.
However, I have learnt from my mistakes, next time I will ensure that I double check before actually making any transaction. I keep consoling myself that I got confused since I was sending different coins to the same wallet.