Anger is my first stage

I’m a mess. After searching online for grief support groups I am not finding the one that I feel I fit in with. I lost my Dad within the past 2-weeks. My first emotion was and still is anger. He was suppose to be ok. He was suppose to have a handful of good years with his new heart. I feel robbed and stabbed in the back. I’m so angry that it was cancer that took him that decided to grow, out of no where, when his heart was healing. I’m angry because we had to turn the heart off. His heart was strong the day damn cancer took him. I just needed a place to vent. I’m not ready to go out and meet people face-to-face in a local group right now. I just needed a place to write what I’m feeling. I don’t know if this anger will last for forever but right now it feels like it. I miss my Dad.