Im in love with her and its tearing me apart.?

I am in love with my ex girlfriend. She broke up with me a little over a month ago. She said she didnt "get the spark." She was very sick (multiple brain surgeries) and i helped her get over her depression. We decided to stay friends and we still speak but not often. I cannot stop thiking about her. I have tried to keep myself busy but every few minutes i catch myself thinking about her, and no matter what i do i cant stop. I am in love with her and i the worst part is i cannot tell her. I know she doesnt feel the same way. if she did she would never have ended it. If i tell her our friendship would be severly damaged if not destroyed. I am extremly depressed and havent felt this crappy in a long time. How do you tell somone you love them if you know it wont lead to anything good, and when you know that they probably dont feel the same way? PLease help. what do i do? btw. i am in my mid 20's so im not a young kid who thinks they are in love.