Is this bad?

Don't get me wrong, this isn't because of jealousy or being petty. Also keep in mind I'm married. But anyways my ex boyfriend and I are still friends, like I said I'm married, and he is dating a girl. Is it wrong that I harp on him all the time that he is dating a girl ALL wrong for him? I'm honest with him, just as I would be to any friend, but this girl is seriously crazy...she's steady asking for all his passwords, checks his phone while he's sleeping, he said "on average it takes her about 12 minutes of me not replying to her text before she starts calling my phone continuously". Asks him where he's at 24/7. She gets mad at him saying he's not really in class and demanded he sends her a copy of his class schedule so she will know when he can't contact her...he has told me he has never cheated on her ever in any sort of way and I'm just like dude this chick is psycho you need to move on and find someone more confident in herself. What should I do? Butt out or give him advice like I would any other friend? Does she go over the edge? She even drew a fake plus sign on a pregnancy test to get him back after he broke up with her..and BLEW UP at him when he asked her to please take a digital test that says "pregnant" or "not pregnant" then admitted to saying she faked it. Now he's back in the relationship and ugh omg it's a mess and as his friend I try to advise him but is it wrong of me to do so since he's my ex?