That my close friend's girl friend hates me?

We went to school together, all 3 of us. I dated my close friend over 4 years ago... And even when we broke up we still remained in good standing. Still hung out with the same group of friends, never one-on-one. Well he just recently told me that his girlfriend does not "feel comfortable" with him talking to me. She's been through his phone and everything, just to see what we talk about because she doesn't take his word -- NOT my problem as far as I can see. If anything, she finally came to me and asked, "Do you consider yourselves friends or do you just like updates? I'm unclear on that." But when you look at it, we had already began talking a lot less because we are both in relationships, and he warned me that she was going to act insecure. She doesn't believe that exes can be "just friends." We've been friends for over 5 years, and yesterday morning we had to end our friendship. We both knew she was going to keep complaining, even after her pretending to be okay with me. She's stated that she doesn't want him talking to any girls of the past, even chicks he hasn't dated... And I'm really sad. I feel like I lost a really good friend. We were friends before anything else. He felt it was the right thing to so he wouldn't put me through anything (according to him). So my question remains, is it normal? Am I in any way wrong for wanting to keep one of the few friends I still have? Or do I just walk away from this? I really have no idea. A lot of mutuals are saying she's being ridiculous but I really can't tell anymore.