his friends that are girls

so we're in our early 20s. been dating for a while. he has this friend who's a girl. thought they were just friends til i found out theyre exs. they dated back in middle school for a few years on and off. he says since meeting me theyre not as close, but i always see her fb chat bubble on his phone. shes in a relationship with another man. she always feels the need to update my boyfriend on everything in her life. my man only updates her on some details, but not all. sometimes theyll joke around and he'll sit there and giggle when we're supposed to be doing something together. just makes me feel uncomfortable that she always feels the need to message him. should i let it slide because he usually messages back with short responses or should i speak up since i feel like hed rather talk to her than hang out with me?... i feel stupid for overthinking this