There are a lot of recomendations for the face to face option here, but I don't know do most of them really know what it feels like to tell someone you really really like or are even in love with what you feel about them and at the same time having no fucking idea whatsofuckingever if they feel the same way. It is crushingly difficult I can tell you that. That said, you should always find a way to tell them how you feel,just to get it out of your system. I once told a girl I knew had a boyfriend for the same just reason, I didn't leave my name of course but I felt somewhat better afterwards.