It's finally time to heat the bolt and nut. Put the flame directly over the stuck part, or the part you can get to safely. Heat it for 30 seconds or so to loosen it up nicely. Unless you're having a really bad day, it should free up quickly. If it doesn't repeat the process to see if that helps. Repeated heating and cooling sometimes does the trick.
Safety Tip: Be extremely careful with an open flame! Never use an open flame near a fuel or brake line. Flammable fluids and open flame don't mix. The flame will burn anything rubber it comes into contact with, including trim, seals, and wire sheathing. It will also ruin paint instantly.