John (the dad) is unavoidable. His house, he pays the bills and is married to Janice.
He's also got ED, and is easily dealt with.
Billy's stuff is optional, and points where the optional content "clashes" (only a couple of times and early on when his optional content becomes available, and tangentially related to Jason fucking his mother) with the mainline game, there's ways around the "clashes" available in game and by design.
Since it's been so long since you played, either start fresh or continue from most recent save/autosave.
Finally, use the walkthrough.