An awkward love triangle

I really need a guy's point of view for this. asap. Mike, Harrison and I are in the same college. Mike and I met during freshman year and became best friends but after a couple of months, he told me he'd fallen in love with me. but i just didn't feel the same way. i tried giving it time but i guess it just wasn't meant to happen. there was no chemistry. he was okay with it though and we're still really close. Harrison is Mike's best friend and roomie. We've got lots of classes together. so we became closer day by day. i've fallen for him completely because he's everything i look for in a guy. recently, he even hinted to me that he feels the same way about me too. but everyone in our social circle knows that David's not over me. even after 2 years. and he's Harrison's best friend. Harrison and I don't know what to do. neither of us want to jeopardize our friendship with David. But we can't stay away from each-other either. :(