That’s a tough thing, and I can understand something of how you must be feeling, as I lost my own father just a few months ago. It is still difficult talking about it. Am taking a while to get through it.
One thing I might suggest is finding some way to talk to him, yes, even now when he has passed on. I’m not from any particular religious faith, but there is actually alot to suggest that our consciousness survives the death of the physical body. What if this were true? What if your dad can actually em>feel /em> your thoughts of remorse right now, and appreciates your good intention? It is possible. And even if you don’t believe in an afterlife or rebirth, you could maybe reflect on how we all must pass away some day, and yet in a way, the best of us sort of lives on- through our life’s work, and especially, in the people we have loved and cared for. In a way, our fathers live on in em>us /em>, whatever impression they have made on our hearts remains. So taking some quiet moments from time to time and reflecting like this might help also. Finally, remember that loving parents do not judge us nearly as harshly as we judge ourselves. I reckon your dad, while appreciating your remorse, would also want you to forgive yourself and move onward with life. That’s what he would probably want. (I know how challenging self-forgiveness can be, I’m working on that one myself!).
Hope something here has been of assistance, and take care.