There is no expiration date or time limit on grief. You are allowed to have these feelings no matter if it's been an hour or 40 years since an event.

Most of us know the 5 stages of grief but contrary to popular belief they don't always come in order and you can experience some stages over and over and some not at all.
You are justified in these feelings.
My personal take on loss is this
It never gets easier and you never forget. BUT it does get more manageable. The metaphorical scars do heal. Pain becomes less sharp and overwhelming And yes the sun will come up tomorrow.
Everyone copes differently. Sometimes seeking professional help is the answer. Sometimes just being able to vent helps.

Bottom line. You are absolutely allowed to feel the way you feel.
I believe in you! You'll get through this.