You deserve more than a one-sided love, always remember that.
No matter who you are or what you've been through, one-sided love is way less then what you deserve.
Listen to me when I say, they are not worthy of your love. You deserve to be loved and cherished for the person you are. You deserve more than a one-sided love.
The love you so willingly give should be reciprocated, and if it isn't, that's your cue to leave. I'm not saying it's an easy thing to do - to leave someone you love with all you have, but if you don't, you're just torturing yourself. Because deep down inside, you know that no matter how fiercely you love them, they'll never love you the same. So, please. Do not settle for something as mediocre as that.
Run.
Run as fast as you can. Yes, you will hurt like hell for a very long time, but you will heal. It'll hurt less than loving someone who doesn't love you back. Go out into the world, find someone worthy of your love someone who will love you back. You will find someone who can handle the fierceness of your love, someone who appreciates your love, someone worthy of you. This person is the one who is worthy of the love you're trying to give to someone who simply doesn't want it.
As hard as it'll be to move on, nothing is harder than being in love with someone who doesn't want you. Know your self-worth, and never lose it.
I can't say it enough but you deserve more. So go. Find it and see where the adventure takes you.
Love yourself enough to let go.