Any shortcuts for grieving the loss of a friendship?

I’ve had an up and down platonic friendship with a guy for over two years. He’s cut it off in a very cruel way. It’s over and I’m sad. I’ll be ok but just want some support and tips for anything that helped you. I know for me that keeping busy with friends is one thing; unfortunately we have overlapping activities that I will skip for now. Please – no harsh put downs.