What Causes Ripping At The External Urethral Orifice?

My external urethral orifice has ripped on the bottom. when you look at the hole you can clearly see that it is bigger then what it is supposed to be. I noticed it about a year ago and just thought it would heal itself slowly but surely, but the rip has gotten bigger. I think it is ripping when I pee/masturbate. What should I do?