Simple answer. 260 Peterson Rd. Is only a 30 minute drive from FWF.
You don't leave your wife and stop living with her just because your parent is sick when you can easily drive over every day to your parent's house plus even spend the night over there to help out. Even your wife could help out. You don't stop living with your family for that unless you do not want to live with your wife anymore.
Canepa said Jake and George did not live with Billy, that they were only living with Angie on Peterson Rd. Angie is the one who always lived with them. I think Canepa meant that Billy lived somewhere else permanently, not temporarily.... My take on it.
But yes of course he still visited, after all, he was there the night of the murders. Hug your grandchildren goodnight before you go out to kill one of their mothers.
And yes, he could have changed his mind after the murders and decided he did want to live with her again and then maybe he did move in with her on Peterson Rd. Maybe murder and mayhem brought Billy home again to his family, it's such a sick evil disfunctional family who knows?
Just my opinion and of course I don't know what really happened in their marriage.
My opinions are probably all wrong since I base them on normal people's behavior and the Wagners are not normal.