Loving someone is painful

I have a man in my life that i love with all my heart, I would give anything in this wolrd to make him happy. Even though he says he loves me he breaking my heart. I feel like such a fool for allowing him to treat me like a door mat. Ive tried to walk away but I simply cant. Im depressed and have abandonment feeling that takes to me to dark thoughts. I know better than to do something stupid over a man. I need to get out of this I just don't how to do it.