PSA: my attempt to paint over old wallpaper went horribly wrong

@william917 is right about steaming it off, but nobody mentioned checking if your wallpaper is vinyl coated. I had the exact same mess in my 1950s house in Oregon - scored and steamed like crazy, still wouldn't budge. Turned out the top layer was vinyl, so the steam couldn't get through to loosen the glue underneath. Had to use a chemical stripper just to break through that plastic coating before the paper would finally come off. Check yours by scratching an inconspicuous spot with a knife - if the surface resists tearing and feels plasticy, that's your problem.