Welcome to this website. I am very sorry to hear of the loss of your father.
I came here in 2017 after losing my mother who I looked after too. She also suffered from heart failure for many years so I know how this complicates any other illness someone in this situation may get. She eventually passed away about six weeks after suffering a major bleed on the brain, partly due to the failure of the doctors to monitor her blood thinning medication properly.
On the day she fell ill, I was at work and she rang me to say she was not feeling very well and was going to have a lie down. She didn't think she needed me to come home, and so I stayed at work for several more hours and left a little earlier than usual only to find that she must have suffered the stroke shortly after she had spoken to me as she had not made it into bed. I tell you this because, like you, I was racked with guilt and pain and anger at myself for not having come home immediately, but that is how life is. At the time, you act on the information you have, not the information you have in hindsight and there isn't one of us who has lost someone who cannot find something to feel guilty about or blame ourselves for.
We all go through the 'what if' process and blame ourselves for events over which we really had no control at all. I am sure it will have been the same for you. It is easy, after the event, to think 'if only' I had done this or that then what happened might not have happened, but that isn't how things do happen in reality. The pain of loss is a terrible one and the shock of it only increases that pain, but blaming yourself for events is not something you should do. No one consciously does anything that would harm someone they love and look after. Things just happen and what does happen is often out of our control and, wish as hard as you might, you can never change them. You just do the best with what you know at the time.
I would urge you to talk to someone about how you feel, even if you only talk to us here, but if you don't have anyone you can speak to at home and don't want to talk too much to strangers here, then you could try asking your GP about grief counselling. It does no good to bottle your feelings up. If you don't want to do that either, try writing down how you feel and say all you need to say in writing. Some people do this in the form of a letter to the person they have lost, so you might find that suits you, but writing the words helps get it out of your system a bit and does provide you with some degree of relief.
Try to be kind to yourself at this awful time. Punishing yourself won't help and is probably very unjust in any event. Sadly, life is an unpredictable business and stuff just happens and not usually as we would like it to happen. In time, you just have to learn to accept that. Sending you a welcome hug.
