I read it back in 2006 and can't praise it highly enough.
I felt utterly bereft after breaking up with an ex and the part that I couldn't understand was that we had only been together about a year, compared to the fact that it when I had broken up with a previous boyfriend after 3 years, it wasn't as brutal even after all that time.
What struck me the most was Paul's explanation of why sometimes it hurts more, and that's because our brains can't tell the difference between what's real and what's imagined. So I'd spent the year planning our future, thinking of our wedding (we had discussed marriage), our kids, the white picket fence, the lot. And of course when that "future" ended abruptly, it completely ruined me. Whereas with my previous boyfriend of 3 years, we knew we weren't right for each other and mentally we'd both "left" the relationship. So whilst it still hurt, it wasn't a devastation.
Reading that explanation just made me realise that I had to start imagining a new, better "future" without him. I started planning a solo trip around South America, thinking of all the adventures I had and within 2 weeks I was in a much much better place. I'd say those 2 weeks were horrendous but it was really a short, sharp breakup. As soon as I started planning a newer, better future, I missed him less and realised that actually he'd done me a massive favour.
I really hope it helps you, it really helped me to understand why it hurts so much and made it much easier to move forward and heal.