The guy I love has been Cheating

I found out he’s been cheating for the last month. How do I cope? I am not angry anymore just feel in shock to my core, how could someone who was that close to me do something so devastating?

It’s been so long I don’t even know who I am without him, I thought we were in such a good place in our relationship until I saw his phone. He couldn’t admit a single thing himself.