Memories

 There is only so much that your brain can rememb
er.

That one person who was your whole life and now isn't will be in your memories forever.
So how do you move on?

Simple, start creating new memories. Start living with new people. Create new moments of happiness with them. These memories will overshadow the old ones.
Memories aren't erased. They are just lost. New memories are the best way to forget old ones. Loose the old one's for the new one's.