Why did my ex add me on snapchat?

So my ex and I have been broken up for almost 8 months and we’ve both struggled a lot with the breakup... it was kind of my fault we broke up, I was mean but I was his first love.. dated a year and a half he ended up dumping me. Well he’s tried to contact me and we’ve hung out since then but it’s never been anything more than a quick talk bc he missed me or whatever. I could tell he still loved me but it’s like he was scared of getting back together. I just saw his mom and young sister at a football game and they missed me so much, his younger sister kept saying how much prettier I was than his gf and asked why I didn’t like him anymore and stuff... me and his mom tried to tell her it was him that dumped me. Well he added me on snapchat two nights later and initiated small talk... then the next day he posted a story of his new gf that said “hey boo” with heart eyes... idk what to think of this, it’s bothering me and I know it’s been a while but I’m still not over him.