NotTheMrMenAgain I am so sorry for you having lost your DF.
It is utterly heartbreaking.
It doesn't matter if your dad heard your mum telling him to breathe and not leave her. If he did he'll know how very much she loved and loves him. Many of us would do exactly the same. When my DF died we knew for just over a day that he would die and, after his last breath, I howled. When I look back I cringe because there were 3 other patients in the ward who I, surprisingly as I'm not a selfish person, gave no thought to. We are all human and I hope they understood my pain and pray I didn't upset them too much thinking about their own demise. It just can't be helped sometimes. I think your DF would understand, especially as he and your DM were together so long.
Your shock and anger is perfectly normal. They help you to get through the initial period of grief. Just go with the flow, howl as much as you like, try and accept whatever you feel.
Your mum is doing what she needs to do. Her wanting to be alone sometimes is ok. My brother and DM were very close and, after finding her body last Sunday, he has wanted some time alone. I am very worried about him too. He is numb. I feel I have to look after him although he is older. We just all have to go whatever we need to do to get through these times.
I am in limbo still waiting to hear if The Coroner wants to do a post mortem. I fluctuate between being totally normal as if nothing has happened and almost silent screaming from my soul in the middle of the night.
Sending love to everyone who is suffering the loss of parents.