Breakup Advice

So I'm 17. I just got out of my first relationship ever September 20th. He dumped me. Via text. Said he had been thinking about it for a while. Said it's not you it's me. Said can we still be friends. Needless to say I freaked out. We had only been long distance for 20 days and he said the distance was too much for him and that he needed someone up under him 24/7 the thing is I'm a virgin so who was up under him? He was extremely emotionally abusive talking about my weight and calling me fat even though I have an eating disorder and he knows because I told him I'm not the type to keep secrets apparently he is because he said he'd been thinking about breaking up with me for a while and and it's kind of funny how just last week somebody hits me up on Instagram knowing a whole bunch of private information about me that I don't tell people like my mental illness come to find out it's his new girlfriend am I overreacting by telling her to leave me alone and that we aren't friends and cursing him the fuck out? I really want to get over this relationship we'd only been together for a year and 7 months and in comparison to Los relationship status and nothing so why is it that I find myself still stuck on him but he's already moved on I wouldn't say that I'm still in love with him because I'm not for him to tell somebody else about my mental illness killed any feelings I felt for him but I can't get over the abandonment issues that I already had that are intensified by him being the emotionally abusive asshole that he is. And exactly what I told him what happened when he went to college coming true. I think my problem is that I know that he must have cheated on me and I can't get over the fact that he wouldn't just tell me the truth. I'm trying not to live in the past, but it's really hard does anybody have any advice for moving on from a breakup?