There are different kinds of loneliness.
Lonely is being in a crowded room and feeling alone.
Lonely is being sexually abused by your father while the
world around you goes on like nothing is happening.
Lonely is thinking that you are the only person in the world
going through this. That there must be something wrong with you for your father
to do this to you.
Lonely is wanting to tell your best friend about the abuse,
but you are afraid of God knows what. Maybe she won't believe you. Maybe she
won't like you any more.
Lonely is thinking that the security of the family depends
on you keeping the secret.