I can understand the distress you are through. Firstly, let me clarify that masturbation or ejaculation does not cause weakness, blindness, and its not a disease. Your complaints are suggestive of premature ejaculation. A condition in which the ejaculation is spontaneous. Night time discharge is common presentation. It may also happen that the time to ejaculation while sex is very short. There is not specific cause to it but multiple factors contribute to it. Stress, anxiety, lifestyle patterns, etc all may contribute to it. With proper medication and instructions it can be completely cured.
Next Steps
You must consult with a sexologist. He can prescribe you medicine and give valuable instructions. You also have an option of consulting directly on practo.
Health Tips
Don't worry. It's not a disease, but a common condition. It is completely curable.