How to become emotionally strong without overthinking , crying , losing intrest in my goals?

Well after crying for many hours, lost power to type but i want to overcome my emotions , feelings also wanted to feel strong for myself soo... in short , i met a senior guy, he studied in my school nd we got connected after he vacated from instagram, we become friends ( like close friends) , then i vacated from his town and our long distance phase started, he proposed me through text , before he propsing i got a little confsn nd doubt as he used to complimnt me everyday and also he used to say 'l like you nd i miss u soo much ' nd ya i acceptd his propsl bcz i felt like he seems to b a good guy.. for six months till decembr of last year our ldr journey was soo good like havn romntc , sweet nd caring convos.. from January his bhvr changes to givin mixed signals nd i felt like im the only one giving efforts and he stopped saying everything openly but whenever i askd him to open up his feelings he will say ' no u r wrong i still love you , i miss you so much , i craves to b withyou , and also each time whenever i see ur message i will hve the urge to meet nd hug you tightly without leaving you ' ... but his mesaging style is completly changed and for many hours and days he is going offline without even saying 'Hi' ... and i feels like im destroyn my self respect by sendin him lots of msges like a joker nd he is playing with me feelings.. I don't know i'm hurting soo much , feeling soo disturbed bcz of his strange mixed behaviour.. and he never open up whats going on his life and what made him like this. whenever i asks him whts the matter , he will just say he cares for you etc but never the exact rsn and i didn't ever felt like he cares my feelings if he does he will open his real feelings and never keep distance.. now im mentally emotionally very down so.. what can i do to overcome from this disturbing emotions like crying , thinking about him and his talks 24/7 , getting distracted from my studies , goals etc..

How to become emotionally strong without overthinking , crying , losing intrest in my goals?
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