Dear Ashley,
Please accept my deepest apologies for my mistake in regard to leaking customer information to people from the other department.
It was not my intention to create such an awkward and embarrassing situation for our department.
If there was any good that came out of this unfortunate experience, it is that I have grown and learned alternative approaches to these situations.
Please feel free to let me of your thoughts and concerns over this matter. You can reach me at email.
Sincerely,
Jim