From all what I hear I am afraid of marriage. Ps I'm engaged and I don't know how I feel about the whole relationship

What have you heard that worries you ?

Your not afraid of marriage, your afraid of commitment. You just ain't ready...

Afraid of failure, afraid of not being good eniugh, afraid of choosing the wrong person

That is dating, engagement and marriage. You chose someone when you date, and often you break up and it does not work out, That is why you date and get engaged and find out more and more about the person, to see if the two of you can work things out.

The issue is, do both people talk and communicate, how do you work out issues and problems.
What happens when you fight over something? Do both sides accept the fact that they may need counseling sometimes.

And what about id I am always thinking that I might find someone better out there!

And you will, there are 1000's of better men out there, but you don't keep looking, you work on the relationship with the one you have. There is always someone with more money, or better looks, or tells better jokes, or one that gets less angry, ** or it will always appears to be, your best friend husband may appear perfect by the way she talks about him.

If you will always be looking, don't ever marry, stay single and play the field for the rest of your life, a new man every few months.

Here's an old joke that may help --

There's a story about a young journalist who interviewed an elder statesman. After he’d put away his notepad, he asked the great man — who was known for appearing at balls and parties with beautiful women — why it was he’d never married. "I spent my life looking for the perfect woman," the old man said. The journalist nodded, thinking — as young men do — that he understood: "And, of course, you never found her." The old man smiled. "On the contrary. Trouble is she was looking for the perfect man.”