Heartbreak

How do you all handle heartbreaks? Over the weekend I lost the guy I was seeing and I'm beside myself. We dated over a year. Our relationship was complicated. We were fwb but weren't boyfriend and girlfriend, but acted like we were. A whole boat load of crap happened last week and the ending result was me losing him. I'm currently in the angry/denial stage. I'm afraid to let it sink in, because when it does I'm going to lose it. I've never been so heartbroken by someone. I love him so much it's insane. What's worse, Sunday is his birthday and I had big plans and I'm afraid Sunday is when I'm going to truly realize it's over between us...