If you merely want to know where you deduct the interest you paid on your mortgage to the bank, that would be under Mortgage Interest, Refinancing, and Insurance in the Deductions & Credits section.
Since you did "sort of a wrap" and are currently paying the mortgage to your lender, I can only presume you still hold title to the property (if the bank discovers this "arrangement" the due-on-sale clause will almost certainly be triggered and the balance will immediately become due). As a result, nothing has actually changed from your perspective; you still own the house and have sole liability for repayment of the note to your lender.
As a sidebar, the "buyer" actually cannot deduct interest payments (as mortgage interest) made to you since those payments are not secured debt.
See https://www.irs.gov/publications/p936#en_US_2018_publink1000229896
