Texted this girl off my bfs Instagram?

So I found out my boyfriend has been hitting up this one girl he knows off his ig commenting on all pictures and trying to get her attention and they know each other but she doesn't pay him any mind. It's not just her he's commenting on but she's one of the main ones and it bothers me so I confronted him and he apologized but I hit her up to see if he was telling the truth and she calls him and starts insulting me calling me immature and laughing at our problem. So he just sits there and doesn't defend me am I wrong for hitting her up?
Texted this girl off my bfs Instagram?
Add Opinion