Hi OP
I'm sorry but you need to leave him.
My brother is in a relationship with a woman whose dad is a convicted paedophile.
She, of course, believes her dad is innocent.
My brother backs his partner. Although he agrees that people don't get convicted without evidence, he supports his partners wish to have a relationship with her dad.
They don't have children, and have been together a long time. They can't have children as long as she wants a relationship with her dad because social services would not allow the children around him. I'm not sure on the rules where you are, but I'd hope they'd be similar.
My brother has also lost contact with us. (His choice) He refuses to speak to the rest of the family now. One of the reasons he won't speak to me is because I refused to allow my children to spend any time at his home, as I cannot trust my brother not to have his father in law there.
As much as I love my brother, I do not trust his father in law. And I would never ever knowingly put my children anywhere near a paedophile, or a paedophile apologist.
So basically, stay and live a child free life, or leave and live your life free from the stigma.
My brother made his choice and not only is he now child free despite wanting children for a long time, he also has no contact with the rest of his family. He has been isolated due to his relationship with his father in law and his partners inability to accept his conviction.
Please don't let that happen to you.