Controversial posts made by AppleScruff

So I'm a confused teenager in her first "relationship". I met a guy 4 weeks ago I think, and fell in love quickly. Long story short we're dating or something now and I live up in the north of Sweden and he lives in south Spain. Our only contact is through whatsapp and instagram. So there is a groupchat on whatsapp with him, 2 spanish guys, my current best friend and my ex-best friend. My ex-best friend is constantly flirting with him and wont stop! She knows that I'm very insecure and that he's my first "boyfriend" but still does it. My best friend confronted her but denied the flirting. She gave him the nickname "edge lord" and sends him memes. On top of that, she makes me look bad when we are all chatting. It makes me insecure and anxious, can/should I do anything?