Grief is similar to physical or mental illness in a lot of ways-- it grafts onto you and seems to effect every little thing. Like a bout of depression, sometimes you just have to endure it without knowing when it will loosen its grip a little. But it will loosen. Humans are still an animal like other animals, and we aren't built to remain in a state of heightened emotion forever.
Gratitude has helped me a lot. Writing stories and drawing pictures where I immortalize treasured moments. Remembering that we are all here for a brief moment and that suffering is something that unites all of humanity in shared experience helps, too. Honestly, having depression made things a little easier, because I'm used to bracing for this feeling of, "things are just going to suck for a while, but it will be okay".
For Christmas my mom gave me a bird painted on a leaf in a little frame from a thiftstore-- probably an old tourist trinket. She wrote the note, "A little bird-- not to keep-- but to hold for a little while." That's life. We feel that sorrow with you-- you aren't alone.