I've resisted replying to this thread because I don't know who has primary custody of your kids. However, if your ex wives have primary custody (and get along with your family) it only makes since that they would receive the invite. Especially considering the other internal squabbles that are occuring.
It makes no sense to me the since I can get them by simply asking. Internal squabble didn't come to a head for me until this. Oh, and my brother's wife's sister's ex husband was not invited.....imagine that.
I personally feel like people don't actually change. Your brother is probably putting his wife first and not putting a different family first. The thing about getting married and heading out on your own is that your form your own family. Your own direct families that you grew up with become second to that. It's a struggle my wife and I, because their family is really close (like, all live within 15 minutes of each other and always think they need an invite to everything little thing - "you went to dinner without us?!"). And they all, at one time or another, ended living back at home and really depend on their parents. We're not like that, and her parents have a hard time figuring that out. We want to be independent. Doesn't mean we don't ask for help or go to family events for both sides of our family, but just means I don't think we have to do EVERYTHING together. We're still very loyal though, and would definitely help out with anyone in terms of illness, but even then its difficult when you have kids, school, etc. You guys already have a strained relationship, and even without that, you'd be pretty stressed out just dealing with your mom alone. But I think you kind of have to look at it from a different angle, without getting defensive that he's doing something wrong. Maybe he doesn't know he is and is oblivious (we've all been there, right?). Maybe he's the type of guy that can't deal with direct stress and hates seeing his mom a certain way. Maybe he doesn't know how to talk to you, since you're always telling him he's doing the wrong things or don't like his wife. He could have already given up.
b****es, man... To be fair, I've had a very odd thing with exes. Just spent 2 hours talking to my ex from college (from about 20 years ago) about how I'd make love to her. (to be fair, she was obviously drunk) I had my ex-wife, who wanted me and our child out of her life for a decade, only to come to me 3-4 years ago, to see if I'd like a new start. (didn't happen) Point is: Be who you are, but always treat a lady with respect. They'll remember you for it.