Welcome to DV!

That is some heavy stuff, everyone makes mistakes though and I'm sure he had long since forgiven you before he passed away. Like I said in a post not long ago, things we fear will happen in dreams often happen. You kinda "fuel" the thoughts by paying attention to them and what you feared would happen actually did. If you know that your fear is responsible for the dream to take the direction it took, you can turn that around and see him without the hell part next time.

Believe in your powers, and if you believe in God why not trust in him and know he'll protect you? Asking things out loud might work aswell, so try that.

Keep on dreaming!