Boyf and girls

My boyfriend and I have been having some trouble lately, and the second we almost broke up, he added a bunch of girls on Snapchat and Snapchat them constantly. I feel iffy because over s year ago he sent girls nudes when we were together but In a rough place. And there's one girl who was my 'friend' that he kissed and he's added her back and it makes me super uncomfortable. He said to me that he's not going to give her up, even if it makes me uncomfortable. But then when I asked if I could talk to my ex (still flirts with me like she does to him) he said no. That's a different story.

What do I do? I feel like he's choosing her over me ?