It might be too late, but you can separate the UV lines like this( if this is what you were having problems with)
switch to Edge, select the UV edge you want to separate
Click the 5th icon from the left on the top row of UV Editor, that's the Separate UV button

Click on one of the UV then go Select>Select Shell, that' will select all the UV in that patch. You should be able to move it out of the way by simply moving it away.

I also noticed that your arm UVs are still cylindrical, you can flatten that out by cutting a seam from where you want it to separate. Select UV shell of the arm, then go Edit UV>Unfold, that should flatten it out. Think of it as pelting a fur off of an animal, it's the same theory. If that doesn't work, then it might be better to google some Maya UV tutorial :(
Good luck with your project., hope this help.