Me and my ex.

I met this guy who ill call ‘A’ I broke up with him this morning because i went through his messages and found out he didn’t want to be in a relationship with me anymore and said that he was losing interest. We met through a friend and Its only been 20 days and i don’t know what i did wrong. Ive stalked his socials, cried all day, and had the urge to text him so much today. someone please help and send tips to get over an ex thanks.