To stop feeling guilty you have to own up to what you did, make amends, and learn to forgive yourself. It is for your own good. Almost all psychiatric problems are caused by intense feelings of guilt and shame over something you did in his past which come back to haunt you. For your own mental health, it is better to come clean and deal with your issues NOW. You need to accept that you did something bad and unjust to someone when they were in a helpless situation. And to make amends, you need to stop being self-centred and learn to have compassion for others. You don't have to tell everyone what you did, there is no need to expose what God has kept secret for your sake. But you must promise yourself never to do that to someone again since your secret has been kept hidden and you have been given another chance to be a good person. You need to learn to forgive the childish part of you that made you do that to your grandmother. We all get selfish sometimes and behave in stupidly childish ways, esp when we are young. But that doesn't mean that this is who we are, or that we are completely bad people. You need to be gentle with yourself. You were young and very distressed at the time and the only way your childish mind knew how to handle the situation was in the manner that you did. But you are more mature now and better equipped to handle things differently if they were to happen again. I'm very sure if your parents knew how distressed your grandmother made you feel, they would have taken her away anyway and put her in a place where she would receive better care and attention. So don't blame yourself too much for what happened to your grandmother. The fact that you feel guilty means that you are a good person deep down inside. There is always a good part of us that makes us feel guilty about the things we did that are wrong and encourages us to do good. Psychopaths don't feel guilty or remorse over the things they do. It is not doing something wrong that makes us bad, but the inability to learn from our mistakes and correct ourselves is what makes us evil. Nobody learns to be good without first doing bad things, feeling guilty about it, and resolving never to do it again. Make amends by deciding to treat people with more compassion and understanding going forward, and never connive to place blame on anyone - even if doing so would make life much easier for you.