Dear @OddTrek38 ,
I'm so sorry to hear that this has happened to you, and that you're suffering the consequences of it even now.
I think several things are contributing to you not being able to process and heal from this - although to be clear, you will never "forget".
First is that your pain, your trauma, your suffering hasn't been properly acknowledged or validated. You've been carrying the wounds on your own for far too long. Part of healing, what we all need, is for others to see our pain and empathise with us, to support us, to cut us some slack, to understand why this pain has turned us into the person we are today. This is a basic human need, and it hasn't been met.
Second, above being seen, you need and deserve the people who carry responsibility to take this responsibility and make amends, however way they can.
Your brother, for what he did to you, even if he was still a child and maybe (athough at 15 it's a grey area) not fully aware of the trauma he was creating. As an adult now, as a father to a daughter, he should know.
Your parents, for not seeing what was happening and not protecting you.
Your family, for the continuation of the trauma and adding layer upon layer of new trauma by judging you rather than examining why you'd suddenly be so negative towards your brother.
None of these people is taking responsibility or accountability. There's no way they can turn back time and take away what happened to you. But there's so much they could be doing to help you heal. You deserved that, and I'm sorry it's not being given to you.
Lastly, you seem to have a very wrong idea of what it means to move on from trauma. Repressing your emotions is never the way you heal.
You're not supposed to be forgetting, repressing, pushing away anything. You deserve to feel. Feeling is how you heal.