Issues with brother’s wife (a bit long but please read)

I am 35 and my brother is 32. We are both happily married with kids. We have been very close to each other since childhood. We are still close however since we are married, our priorities have naturally shifted. His wife of five years and I share a reasonably cordial relationship. But it has been deteriorating steadily. She is usually friendly on the face but then there are times when she will have an attitude ‘just because’ and by that I mean she will stay quiet and ignore me when I am visiting. She has always had an issue with my closeness to my brother. Also, there is this constant competition of being the better of the two. I have excelled at academics and my family turns to me for advice on certain matters. She has, in subtle ways, expressed her anger at it when it comes to my brother. He has gradually stopped talking to me all that much about stuff. I am ok with that to an extent because the attachment is what matters to me and not who he choses to confide in. Its not a battle. She is the wife and deserves that. But as a sister, I think it should be ok if he also talks to me about stuff where he thinks its ok. Well the real issue is that she manipulates a lot of things that I say or do in front of my brother and surprisingly his image of me is changing. For instance she says I worry excessively about my baby and she, on the other hand is a ‘relaxed’ better mom. He has actually called me ‘overprotective’ and compared me with her in issues including breastfeeding (she could do it without Lactation Consultants, but you are so anxious that you go to one even though you don’t need one for something so natural). She is slowly building my image as a sensitive ‘wife’, overprotective ‘mom’, lazy (I go out of the way to even help her out with stuff), a daughter who manipulates my mom, an insensitive daughter in law etc. Like everything I do is ‘wrong’ and then glosses it up with but “you know she has always been like this, she doesn’t do this intentionally”. On top, there are times when she says regular stuff but in a rude way. My brother thinks its ok once in a while. Family does that here and there. Well, I have started to feel disrespected and have started maintaining a reasonable distance. My brother’s attitude hurts me but I also do not want to ruin our relationship, for our sake and the sake of our parents. Any suggestions?

Update: I have tried talking to him in subtle ways but he thinks there is nothing wrong with her, she always says good things about me and wants the best for me. It has led to arguments so I avoid the topic now. I posted anonymously coz she maybe on here too.