breakup

my boyfriend and i we broke up two days ago after almost a year, yesterday i found out that he was texting with a girl from my school about for a month. then i know i found out that he unblocked his fuckbuddy on whatsapp and they're once again talking. we broke up but we told each other that we still love one and other than he does this. he promised me that he won't be able to connect with another for a few while. but it's been 2 days, he seems to forget everything we have built together. 2 days ago we cried together because we had to broke up (things were going bad so thats why we decided that) what should i do? i was planning on being single for a while just to respect our relationship but now it breaks my heart to see him this way