Boyfriend Ex.

So hey ladies.. me and my boyfriend recently just got back together after being broke up for 2 months. I completely cut off everyone I was texting or whatever, but he still has his ex on Snapchat & they always texting each other. She he just sends him a streak of her in the tub / text him about something he posted.. do I have the right to be mad at this? Because im not conversing with ANY of the people I talked to in the past. Me & him have had multiple conversations about it, and he always say that I’m just getting upset for no reason and that they don’t really talk about anything.. advice please.