The harsh reality is that most people have a hard time forgiving someone who's hurt them deeply -- and the deeper the hurt, the harder it is to forgive. This doesn't excuse your family for their unforgiving attitude -- but at least it may help you understand it. Self-centered people, the Bible says, will always be "without love, unforgiving" (2 Timothy 3:3).
At the same time, you must be careful that you don't fall into the same trap, by failing to forgive them for the way they've treated you. An unforgiving spirit not only fails to solve anything, but it acts like a poison on our souls. You cannot harbor anger and bitterness in your heart without bringing great harm to yourself. The Bible warns, "See to it... that no bitter root grows up to cause trouble and defile many" (Hebrews 12:15).
How can we forgive those who have hurt us? I believe it's only possible when we realize how much we've hurt God, and we seek His forgiveness for our sins. We don't deserve to be forgiven -- and yet God in His love and grace offers to forgive us because of Christ. Ask Him to forgive you and come into your life today.
Then tell your family (perhaps in a letter) that you're sorry for the hurt you've caused them, and you hope they'll forgive you. It may take time, but God can change their hearts -- just as He will yours.