It seems that one of the reasons that x-lite can still reach the domain is because you don't have a separate line with an IPv6 loopback (an IPv6 version of the 127.0.0.1 address the blocked domain currently redirects to). x-lite must be ignoring the IPv4 entry, and connecting to the blocked domain via an IPv6 address.
You can fix this by adding one line to your /etc/hosts file. A similar question HERE suggests that you use fe80::1%lo0 as the IPv6 loopback address, as it says that OS X versions later than 10.8.2 won't respect the ::1 loopback address.
An example of the line you need to add to your host file is:
fe80::1%lo0 DOMAINTOBEBLOCKED.com If this doesn't work, I would suggest having a look at some of the other answers on the question above. One that looks promising is:
Try adding following line in /etc/resolv.conf
lookup file, bindThis should force OS X to use /etc/hosts before dns. The only problem is if you use dhcp, this file will be overwrote each reboot.