The TFRP equals the trust fund portion of unpaid payroll taxes assessed against any responsible person who acted willfully. Willful does not require fraud. It means you knew the taxes were due and chose to pay other creditors instead.
You have 60 days after Letter 1153 to appeal. The Form 4180 interview is adversarial. Do not go alone. Multiple people can be responsible persons for the same liability. We defend responsible persons against TFRP assessments.