Context: The Bride: the sweetest creature imaginable. Main concern is walking down the aisle to her intended and living happily ever after with him.
The Groom: besotted with his intended. Main concern is the bride walking down the aisle to him and living the happily ever after.
Mother of the Bride (MONster) has seven children, antagonistic, obstructive, anxious not to lose her chief babysitter/child-minder.
The Wedding Planner: well, that's me.

So this is the letter I would send to MON if I could.

Dear MON

I hope this missive finds you in good health. Can I suggest a little pre-wedding holiday to soothe your frazzled nerves? I hear Mexico is quite lovely this time of year. I think one can get a substantial discount on flights at the moment. Just a thought.
Obviously, you see it as your role to be both supportive and honest with your daughter. However, telling her that her wedding dress is "Immodest and totally inappropriate" isn't going to win any hearts. Telling her that she "needs to wear a shawl or cardigan to cover up" isn't all that nice either. (For the record, it's a perfectly lovely, strapless gown)
And by the way, I'm not wild about the fact that you want the wedding invites to stipulate that female guests MUST wear veils or hats to the Church. (It's a modesty thing apparently) That's just so 1400's!

I know it is important that this is an occasion where you get to be in your favourite place, centre-stage. But, and obviously, this is awkward for me, it's actually not YOUR wedding day. So whilst I will happily arrange a special corsage for you, as well as having your daughter pay for your make up and hair, I do draw the line at her paying for your wedding outfit. Unless of course, you want to do a trade off and pay for hers.

Now I know, that despite the fact the Bride and Groom are funding this wedding themselves, you feel it is important you play a leading role in the affair. Absolutely. I agree. I think that you are VERY important. But denigrating the floral arrangements, the wedding invitations and the bridesmaid dresses and saying you could have done it ALL yourself, and for much less money. Well, no you couldn't. Simple as that.

And finally, the Bride and Groom are working FOUR jobs between them to pay for this wedding. So trying to add "near and dear" friends to the guest list just isn't going to be possible, Especially when at least 70% of the guests are your friends anyway AND they have to fork out the airfare for your brother to fly out here for the occasion.

I think that's it for now. And do think about Mexico won't you?
love
Seraphim.