Richard Sockett was locked out of his branch and told to pay nearly £12,000.
Richard and his wife took over the post office in Barton, just outside Cambridge, in 2003.
His family enjoyed nine happy years in the village, before everything changed in 2012 with arrival of a new Horizon pin pad.
Richard has been speaking to Star Radio about when the issues began:
In April 2013, within two hours of a Post Office auditor arriving, he was locked out of his branch and told he owed nearly £12,000.
His elderly father had exactly £12,000 in his bank account and said "Take every single penny I've got".
Richard says he will never forget the day it all happened:
Richard, now 65, has since received some compensation through the Post Office's Horizon Shortfall Scheme, but not before his father's death in 2016.
He says the Horizon scandal left him depressed, quick to temper and get distressed, and his relationships suffered.
Richard says he felt like a failure who had let everybody down:
Richard was one of more than 700 sub-postmasters who were prosecuted over claims they were stealing from the Post Office - but the missing money was actually due to errors in the Horizon software, which was developed by Fujitsu.
The ITV drama Mr Bates Vs The Post Office, which was broadcast earlier this month, has raised the profile of the inquiry and the injustice suffered by the hundreds of sub-postmasters.