This is exactly why I don't open up to people. What if they don't care about me as much as I thought they did? They to HAVE to show me exactly how much they care about me before I feel confident enough to open up to them.
One of the keys to success is passion. If you care about something or want it naturally you won't need to force yourself to work on it. The passion will be your fuel. Only work on things you are passionate about.
The person might not be who you thought they were; might have changed for the worse; but in the memories, they will always be the person you loved. it's ok to cherish those memories. You dont have to allow that person in your life now.