Any idea when do you think it will be fixed?
No. Not at least till it gets dropped or a transaction that spends that output gets confirmed.
I would recommend you to just switch to Electrum. PM me if you need help regarding this. Else, there are various tutorials on this on Google.
But I never did anything like double spend how did that happened.
Have you tried spending the coins again after seeing it being returned to your address? You likely tried to send the coins again and the website saw that there is a conflicting transaction and labeled it as a double spend.