Need pep talk before interview?

First of all they are lucky to have you.

You are leaving for promotional opportunities that aren't available to you in your current position. Don't mention not stealing customers, you have built some good relationships and if they would like to continue with your good service you won't hold it against the. That they do business with a current t employer.

You are respectful of your current employer and you appreciate the experience they have you. Sometimes though..you have to make a change.

You would not be interviewing with them at all if they considered you unworthy in any way. In fact they probably want the skills that you have that made THEIR largest competitor so great. When you go in to the interview remember that they already want you....even if it is just to shoot their competition in the foot. You can have that confidence, knowing that they have probably already decided in your favor. When you go in, smile, shake hands, and say "I hope you'll excuse me in advance. I am feeling a little nervous." Much will be forgiven if you are charming about it.

First of all, hopefully they won't pry to who your customers are.
Hopefully the dialogue will be your customer relations on how you got them....
be yourself

Just remember to reflect the fact that you're an experienced professional looking to 'better' themselves.

Be polite and respectful

You got this !!

Just undo your blouse a bit.... ;)