Problemmmm

OK so long story. I met this girl about a year or two ago and when I first met her we instantly became friends because I was super open with her. She was more boy obsessed than me, but I was there to listen. She met my older sister (She's 13 or 14 and my sister is 18 now) and they also became close. I didn't mind ofc bc I'm not bitter like that. She also met my cousin who's my age and she and him became friends too. I don't have insta but the three of them do. They would message frequently and I didn't mind, I'm not very chatty online. But recently, my sister and her spend HOURS talking together and even have BFF necklaces(we also have trio ones). I also didn't mind, because their interests are more aligned. What really pissed me off tho is that they started doing 3 way calls on insta. Again, don't mind that, but also 3 way calls on the number??? Like I feel purposely excluded and it's made my depression and suicidal thoughts increase because I really don't have anyone. I don't want to bring it up to them because I know my sister loves me and my cousin has encouraged me to not commit suicide when I was in the middle of a breakdown. I might be selfish because I talk to my cousin almost everyday and I literally live with my sister. I don't really reach out to the girl but when I do she's super dry if she even responds at all. I don't know what to do and everything sucks. Thoughts? Opinions? Prayers?