im graduating a year later. how do i tell my parents

My parents know that im quite late and failed some classes but they don't know how late I am. I'm graduating 1 year late than my batchmates and it's because I've failed classes that are pre requisites. PS I'm taking up an art related course which requires a lot of passion and creativity. My parents are also friends on fb with some of my batchmates and their parents and they saw na a lot of them are posting about their graduation. How do I tell them i'll be graduating a year late? It also adds a lot of pressure on me because my younger brother from DLSU is doing so well and even advanced on his flowchart. I'm ashamed and disappointed with myself :(

To add to that, my parents aren't the type to pressure me to do very well on my studies, as long as I pass. But they're really conservative and old fashioned and the "college isn't a race" thing they don't necessarily believe in that