Boyfriend talks to ex everyday

My boyfriend talks to his ex on Snapchat/text everyday and I will just see him do it and he said there’s no feelings at all, but back story, they dated for almost a year, she cheated on him twice and then moved so they broke off because of the long distance. after 2 months of them breaking up we started dating so it’s new. I just don’t know how to deal with my insecurities, i just don’t understand why someone would even want to be friends with someone who cheated on them twice..

How would you deal with this situation?