Don't feel guilty, even if you never decide to talk to your dad about it. You didn't do anything wrong and it is not your responsibility to make it right! Do what you feel comfortable doing at the moment... everyday you will dare to venture a little further as the time passes by. If you feel that you will benefit from telling your dad, no matter what the aftermath, then do it. You know he will need a little time to adjust to the information, so don't feel bad at his first reaction... it's just his instinct. It's better to be prepared for it and expect the worst and hopefully he'll come round soon enough.
I wish you all the best Simon!

Tanya