Find another support, put the transformer or whatever at the soffit ventilation, and run the entire length of the antenna outside, to your 12 ft. point on the tree (unless there's some way to get it higher) and then to your second support. Bend the wire to fit if necessary. It is more important to have the high-current points on the antenna high and in the clear than it is to have them in a straight line. Having the high-current part of your antenna inside your attic, a few feet from your house wiring, is likely to cause interference to and from your set-up. You will be much happier with the antenna outside! As others have pointed out, you will want to address lightning grounding; in addition, if it were me, I would make provision to lower the antenna in foul weather and have as much of it as possible lying on the ground when lightning threatens.