I was compromised to enter iCloud data by intruders and now blackmailed with device lock or money

hello, I wanted to sell my ipad which I used for a long period of time.  I posted it on the sales site.  A person wrote to me that he would like to purchase it, but he has problems with logging into his own account and he will purchase if he can log into his account on my device.  I entered the data provided to me, a second later they show me that my device will be blocked and I am blackmailed so that I would throw off money for my own device.  Can you help me get out of the intruders' account?