Doubt and contradiction in buddhas teaching

I have few doubts in buddha teaching. Just wondering my mind since i start reading the various teachings. 1. Lets assume we all achieve the enlightenment then what will happen to world? No one will exist .. no life will exist... that will be the end of this universe. 2. If we really know the path then why even one percent leaves behind and could not achieve nirvana. 3. Buddha says we lose what we cling to. But he talks about love too. Loving your son or wife will bring attachment for sure. What one should do when a person rapes/molest your close one in front of you? Anger and emotions will take over.