killinspoon: One difficult thing about ending a relationship is re-establishing your identity because you feel like you've lost part of it. Among your network of peers, you and your former girlfriend were probably known as an item - so whenever social events were organised they'd usually invite both of you I imagine. So now what you need to do is to focus on re-defining your identity as an individual and not as one half of a partnership (as that partnership has dissolved).

And as a general rule for problem solving, always ask yourself, "Will this make things better or worse?" -- yes, you're hurting a lot now... but you need to consider whether or not your attempts at healing yourself is actually making things better or not.
e.g.
+ Focusing on your pasttimes and hobbies <-- helps
+ Spending time with your mates <-- helps
+ Alcohol abuse <-- not helping

You want to find things to help you in your healing process and not add to your existing problems.