What do I do to move on?

Six years ago I fell in love with a guy that was my best friend at that time, i thought he felt the same but obviously he was just a nice guy; stuff happened and we kinda broke up. I did everything i could at that time to move or forget about him but not a day passed by without me thinking of him. He lived and still lives in my head rent free. The thing is after many years we returned to each other and this time i, well , i confessed my love and he just turned me down( in the most kind and respectful way for you to imagine:'). After few weeks i told him I can't keep going with him anymore so we broke up for the sake of me to move on and he understood it. Gosh he doesn't give a shit about me. Tho we broke up but nothing changed in my head and i feel like im catching depression i can't do anything. Any tips guys for moving on?