Dear Anonymous, 

The change you are looking for is not going to happen on its own without your cooperation. It is going to have to be an act of faith.  

Faith is not a feeling, it is a strength and a light that will allow you to correct the negative images you have of God. Faith is not irrational, but based on realities. The negative images are 'imprinted' as you said, so they are emotional, not rational. They condition you despite what reality says, they are a kind of obsession (just like the person who is obsessed with germs will see dangers where you and I don't, won't shake hands for fear of contagion, etc).  

You need to focus in on God's love. Just look at what he has done for us - could anyone love us so much as to die for us? Could anyone love us so much as to give his son up for us? Yes, read the Bible, but especially the New Testament (also the mercy passages of the Old Testament, where God speaks about all he has done for his chosen people, his patience and love).  

Maybe your image of God makes you react to the sacrifice of Christ by saying how harsh God is to ask that of him... That is where you are going to have to shake yourself and say with Saint Paul, how amazing it is that when we were his enemies Christ gave his life for us so we could become his friends. Who else has loved you that much?  

When you go to confession think (and thank Christ) how he did everything so that sin could have no permanent hold on you. When you go to Communion think and thank Christ for being there for you, to nourish you and give you strength. Drop in to visit him in the church now and again, and see how he is always there for you.  

When you think about your own course in life, your experience of how weak and unjust humans can be, even those you might most expect to love you, compare it with what Christ has done so as to see his love.  

I think you may tend to confuse feelings with realities. We all do. You will have to overcome the feelings of dread you still might have for a long time in dealing with God with the light and truth your faith gives you. Don't be surprised if it is a long struggle. Even when your convictions grow as regards God's love you might still be embarrassed by having the same feelings, and you may feel this as a conflict, and think it ridiculous to feel that way.  

Don't worry; wounds from childhood take a long time to heal and their effects may never disappear totally, but you need to be able to say to yourself: those are remembrances and feelings, but I know God loves me, and have seen how he does.  

And pray. Pray with all your heart and ask Christ for the grace to know him as he is, to know his love. He will not turn you away.