in love with best friend

I am in love with my best friend. He said he liked me for a long time, and I friend zoned him for so long because I didn’t want to ruin our friendship, when I finally confessed my feelings for him he said he liked someone else now, and that if I told him a month ago how I felt things would have been different. my question is, can someone who liked you for 2 year loose feelings for you in 1 month? I just feel so sad and shitty bc I friend zoned him and now I have feelings and he friend zoned me, when I would feel sad or someone would hurt me he would be the one to comfort me and make sure I was okay, but now he is the one making me feel sad and who hurt me and I don’t know what to do, I need to get him back