Welcome to MS.
I am glad you have found this place of healing and support.
I am sorry that your parents have denied your experiences and chose to turn the other way rather than deal with the trauma you were experiencing. Being abandoned in that regard is like being abused all over again. They sent a lot of hurtful messages to you. They chose to do what was confortable for them (ignore the abuse) rather than what was in your best interest.
You may have difficulty speaking to your sister, but she sounds like someone who would be receptive to hearing the things you want and need to say. In time you may find that you are able to face her and develop a healthy sibling relationship.
There are several books you might find useful.Scout's Honor: Sexual Abuse in America's Most Trusted Institution
. Due to the price of this book you may want to borrow it from your local library.
Abused Boys: The Neglected Victim's of Sexual Abuse by Mic Hunter
Victims No Longer by Mike Lew
I am certain others will share titles they have found useful. You can find these titles, and others here at the bookstore
Take your time and look around. You do not want to trigger yourself by reading too many posts at one time.
At your own pace, read the boards and wander into chat. The lounge (chat) is open 24 hours a day though it isn't always populated.
We also have moderated chats called Healing Circles.
They meet on Sunday and Wednesday evenings at 9pm eastern time and one on Tuesday at 19:00 UTC (European and African time zone) which translates to 2 PM Eastern US time zone. The Healing Circle on Tuesdays is scheduled to resume in January.
Again, welcome to MS.