Ouch, you do have a mess. May I strongly urge to visit a local paint dealer and get a couple of references for painters who specialize in this type work. I realize you have had a bad experience, but this is a task you might prefer leaving to someone who has experience in this area. If you are not comfortable, repost your question with more detail and I will try to help guide you.

Details which would help are… How many layers of wallcoverings? How many layers of paint? Is there crown moulding or chair rail in the room? Are the walls sheetrock under the wallpaper? How old is the house?