Boys trouble

So I’ve had this crush on a boy since year 8 so nearly 5 years now I’m in love with him we had always been close in year 9 we almost dated but idk what happened year 10 we drifted away and year 11 he dropped out then he told me he was moving back to Ireland and that when I lost it I didn’t know how to cope everything I heard about live and sad songs remind me of him I’d cry every night before bed but he didn’t move we still talked every so often but it’s not the same as it was he has completely change into someone idk anymore, he texts me and wants to hang out but he isn’t the same but the thing is I can’t get over him I’ve said he is the one and all my friends say if not now you’ll find eachother later in life and it will be right I really want him like i want to marry him but idk I need to get over him there is something that stops me from letting go and idk what that is ? So how can I get over someone that’s been a huge part in who I am today?