If ignored, shin splints can develop into a stress fracture. You need to be very careful!
If the pain is bad enough to leave you limping, then unfortunately a half marathon is not a good idea right now.
Having said that, I carried on running when I had mine. I eased up the intensity of the training and when i did go out I ran very slowly. Combined with Ice, Ibufrofen and physio sessions, I was OK.
Best of Luck if you decide to run on Sunday, but take it easy!