Westgate has possibly the worst reputation of all the timeshare systems. and that is saying something.
Get your letter into the mail. NOW. Send it certified so you have proof when they receive it. They have to accept it, but they don't have to tell you they did. The letter is a simple " we are rescinding contract #" and sent to their address in Florida. Look through your stuff; it's in there someplace, but Westgate (commonly referred to hear as Wastegate) hides in; look for a hidden pocket.
Once that is done, if you are still interested in a timeshare; do your homework first to determine which system is the best fit for you and then buy resale. Orlando is full of timeshares; pretty much every system has something there. Think about the other spots you want to visit and buy a system that has the places without a lot of timeshares. or start by renting. But stay away from those promotional stays where you just have to sit through a 'short' (never happens) presentation where they strand you someplace in the boonies when you don't buy from them.
Here are some similar threads;
Westgate rescission 1
Westgate rescission 2
This one has the address; see posts 26 and 27
Westgate 3