Ig girls

My bf constantly add girls on Ig and I get really insecure, he claims they are old friends and gets kinds defensive every time I ask him who are they. I have no way if knowing who this girls are because I don’t know them and only have his words that they are friends. I have really big trust issues and I try really hard to trust him but every time he adds a new girl it triggers something in me and I get really upset and insecure. Any opinions or comments are welcome. Am I wrong to feel this way? Is it me? Or he shouldnt be adding girls like that? IDK... pls help.

Btw We’ve been dating for almost 5 years are we are 25.