Here is a revised email with kind of a combination:

"I agree, I don't think their wedding is an appropriate time to discuss this matter with anyone.

Here is their website: http://www.website.com

I have cancelled the room reservation and will not be staying in city of wedding.

I had planned to purchase a gift on my own but if you would like to purchase one together please let me know what you send them.

See you Saturday at the wedding!"