Shawn Mendes has postponed his world tour to focus on his mental health. The 23-year-old singer told his fans in an emotional post on Instagram that returning to touring had been “premature” and he has hit a “breaking point” so he needs to take some time off. He wrote: “This breaks my heart to have to say this, but unfortunately I’m going to have to postpone the next three weeks of shows through Uncasville, CT until further notice. “I’ve been touring since I was 15 and to be honest it’s always been difficult to be on the road away from friends and family. “After a few years off the road, I fel…