Re: what would you do?
Its hard to say really.... i think all the excitement for your wedding and the reaction you were getting from everyone made her realized wht she missed out by not having a reception in the USA. its fine that she's doing a reception finally. But honestly i think she is wrong with the choices she is making now.
she had her wedding and now its your turn to shine and she should have respected that and if not waited after your wedding at least do it weeks before and not so close to yours.
I dont think your over-reacting, she should have been considerate..especially when she choose her mehandi function the weekend before yours. and all the mehandi functions i've been to in Canada are always on the weekend, so not sure about a weekday mehandi...
Overall, its your wedding day and you shouldnt let others interfere with your happy day...so just ignore it but she is wrong with her choices. Enjoy all your upcoming days they go by so fast!!
Wish you all the best with your wedding and preparations!!!