I don't know what to do

My entire life (I'm 38) I've only ever lost one person unexpectedly. A friend when I was in high school. The grandparents I had lost were expected deaths, I was very young for those except my grandmother who passed a few years ago, but we weren't very close. I guess I had been fortunate to have not had many experiences with loss. 

But now, here I am trying to learn how to cope, to breathe, to live. My dad, my hero, took his own life on September 7, 2026. To say it was unexpected would be an understatement. My mom and I never saw this coming, despite his depression and medical issues...we would have never thought he was even contemplating taking his own life. After he died, we found posts in suicide support groups going back over a week, but he never even hinted it to my mom. They had a great day together, watched a movie, drank some wine in the evening and after she went to bed, he went for a gun. 

I can't wrap my mind around it. How he could leave her, 42 years of marriage and they loved each other more than anything in the world. I can't understand how he could leave me, leave his grandsons....nothing makes sense to me. 

My work put out an email a few weeks ago about suicide prevention month, I went and ordered a shirt and some pens and such, and I remember thinking how I didn't know what I should get because I had never been through this type of loss and wasn't sure what was too much etc. ... it was all delivered the day after he killed himself. And as crazy as it sounds I'm wondering if I somehow jinxed my own reality. 

My dad was very vocal on ***, and I would often get his comments/posts on public forums on my own feed. I usually rolled my eyes because it was silly or political or pug-related lol. Why didn't I see his post on the support group? it was a public page and he posted on there Aug 29. So I'm left with more confusion and more anger because I could have done something....I could have helped, I could have tried. 

I am so angry, and I am so broken. How do people do this?