I read one of the books by that spiritualist medium Gordon Smith a few years ago - it is called 'Through My Eyes' - and in it he describes a situation where a woman visited him and he made contact with her deceased father.
You may or may not believe in such things, but it transpired that this man, her father, had abused her as a child. Suffice to say there were lots of anger and hurt but the woman appeared to find a kind of healing. I am not saying that you should seek out a medium but perhaps if you read up on the spiritual you might find some comfort there.
I personally believe that we all come here to learn life lessons. I also believe that many of us are locked in 'family loops' where the sins of one generation, (and I don't mean biblical sins here but rather personality traits), get carried on from one generation to another until someone breaks the cycle of the loop.
So reading about the childhood that your father experienced in his diary, whilst it does not excuse him for what he did, it might help you understand why he did what he did and, in time, to forgive him.
There may well have been a cycle of anger, hurt and abuse going back in your family for generations - passed down from one generation to another. Perhaps you will be that person to break the cycle? Perhaps you are the one who will come to understand what has gone on for so long and why it has gone on? Perhaps you are that special soul who, through forgiving your father, will actually forgive the wrongs and hurt of many generations of your family past?
As a spiritual person I do believe that the actions of the living can actually heal the souls of those who have passed on. Perhaps some of us just come here in order to heal the lives of those in our family who have already gone... if that makes any sense.
You are clearly a kind and loving person - you would not be feeling remorse and guilt if you were not. Such feelings can over-power us with negativity but please try and look on them for the positives that they are - they show that you are a good, kind, loving person.
Yes, you have regrets. But regret is a two way street. Your father would have had regrets also - it sounds as if, perhaps, the diary was a way of him trying to voice his regrets, his way of trying to reach out to you.
If you believe in an after-life you can reach out to him if you wish - you can talk to him. Have a conversation with him as if he was in the room with you. Talk to him about what happened, how you felt then and how you feel now. Let it all come out. Even if you do not believe in an after-life talking to your father might allow you to work through and resolve all the hurt and anger that is no doubt inside of you.
I wish you all the best. If you need to see a Counsellor then there is a lot of good that can come from talking with one - ask your GP about seeing one. Also consider reading books on spiritualism, if that is something you are interested in, or reading some of the books on self healing.
One of the finest books I have ever read, and which helped me enormously when awful things were happening in my life, was a book by the hospice pioneer Elisabeth Kubler Ross called 'Life Lessons: How Our Mortality Can Teach Us About Life and Living'. There are chapters on Love, Loss, Anger, Fear, Guilt, Forgiveness and Happiness. If I had my way everyone would read this book.
You sound a lovely, kind soul and I wish you all the best. I will leave you with a quote from Elisabeth Kubler Ross:
?The most beautiful people we have known are those who have known defeat, known suffering, known struggle, known loss, and have found their way out of the depths. These persons have an appreciation, a sensitivity and an understanding of life that fills them with compassions, gentleness, and a deep loving concern. Beautiful people do not just happen.?
www.ekrfoundation.org/quotes/