Host says that I've been hacked!

From my host:
rjolley@smartretirementinvestor.com,

This notification is to inform you about a problem with your site hosted on XXXXX, robertljolley.com. This site appears to have been compromised and was being used to send spam. The HTTP logs showed lots of suspicious request to this file, which appears to contain malicious code:

/home/cp23350/public_html/robertljolley.com/wp-content/plugins/google-analytics-for-wordpress/frontend/error.php

The wp-content/plugins/google-analytics-for-wordpress folder on smartretirementinvestor.com does not even have this folder.

I can provide the code from the error.php if you wish.

http://wordpress.org/extend/plugins/google-analytics-for-wordpress/