Frist, I agree they kind of set you up and that’s not very nice. If they were set on this timeline, they should have presented it that way. If they ask, it isn’t wrong to give your opinion, so don’t feel bad. But as far as how to react to their timeline there are a couple different issues here:
1) Your concerns with having the wedding a month or two before yours
2) Your parent’s concerns with having the wedding a month or two before yours
3) Guests concerns with having the wedding a month or two before yours.
These are all seperate issues and should be treated as such.
1) Your concerns – I can actually speak from experience on this one. I’ve been engaged since Feb and two days ago my sister got engaged. I’m so excited for her. All I asked is that her wedding not be on the same weekend as my wedding. If she wants to have her wedding a month or two before mine, then I don’t see a problem with that. I’m also strongly suspicious that my fiance’s brother will get engaged soon and we’ll have the same request for them. So I say, be excited for your brother. Their wedding would be a month or two before yours. Not a big deal. Your wedding will still be awesome and special. Their wedding is just as important as yours. You don’t get dibs just because you got engaged first.
2) My parents have asked that my sister plan her wedding to be at least a month apart from mine they can have time to recuperate. This seems reasonable to me, and my sister thought that was reasonable as well. But this came from them. Also, finances are another issue and one you shouldn’t be involved with. We’re paying for our own wedding, so it isn’t really an issue for us. You you, I would let your parents worry about any money they plan to contribute to either wedding. And if yours is a bit less, make it work or contribute more yourself.
3) I would also let your parents worry about guests. If most guests don’t have to travel too much for the weddings then I don’t think it’s an issue. Guests will work it out one way or another. At most, you could mention that you’re concerned for so-and-so having to travel so close together, to make sure they’re aware of the potential issue, but then I would drop it.
The bottom line is that as much as we want weddings to happen in a perfect fairyland where everything goes right all the time, weddings actually happen in the real world. And in the real world there are a lot of other things going on, besides your wedding. And those things are important too. So take a moment to mourn the passing of your ideal wedding situation, then move on. Congratulate your brother. Plan an awesome wedding. Try not to stress. Pick your battles. And if you want a great blog about why your should pick your battles carefully:
http://thebloggess.com/2011/06/and-thats-why-you-should-learn-to-pick-your-battles/
The link is mostly because I think it’s hysterically funny. But anyways. Good luck with your wedding and with your family!