I am bought by the yard but worn by the foot. What am I?

What starts with E, ends with E, and only has one letter in it?

Promised made, and forgotten all the same; this is the message of the full-of-sh!t leaders to blame. Democrat or Republican, my truth is only for me, and it's for free. End-by-end, all I talk about is this... Which needs many stupid slapped, repeatedly upon the head.

I walk in a suit but own no tie. I have two wings but never fly.

I have layers of secrets and a crown made of sweet, whipped delight. I am baked for a celebration, and I disappear with a glowing light.