I'm afraid for M when your dad is a child abuser it's a hard sell that you are living an aspirational life.
One of the terrible things for the families of men who turn out to be child abusers is the sense of shame or being tainted by their albeit innocent association with such evil.
It's horribly unfair but very common. Families often want to move, start afresh, or live very quietly because their past relationship with such an sick abuser haunts them.
I know people who have lived through something similar to this situation. It's terrible and life shattering to discover someone you trusted is an abuser.
I think the vileness of the alleged crimes are being overlooked here. The details provided are stomach turning even in their brevity.
This horror if true is going to be something that haunts M and the children to have such a grandfather.
I'm really not sure the 'I'm living a dream life' shtick can work once your life is actually an obvious nightmare.