Unable to access WP admin

Question

I cannot access admin via:

http://example.com/admin

or

http://example.com/wp-admin

Fatal error: Class 'ObjectModel' not found in /home3/xxxxxx/public_html/example.com/wp-includes/class.wp-dependencies.php on line 28

I have had a trojan on my website that will put own .htaccess redirect stuff. And what is worse the WordPress version was up to date 3.5.1 and I have almost no plugins installed.

File permissions were 644 and directories 755. How can it write to .htaccess?

What file permission should I set for .htaccess?

I am on a shared Justhost hosting.