When you click on the line, do you get a small box at either end of it? Or does the insertion point sit in the middle of the line flashing?
If you have no other option, copy the information from the Word document into a new blank document, all except for the dreaded line.
As for your question about the lines not being justified, this is due to different character widths - for example a letter "i" is a lot thinner than a letter "w".
To get round this, and probably a better solution for your needs, right-click in the toolbar area at the top of the screen and select "Drawing" from the menu.
The Drawing toolbar will open - either docked at the bottom of the screen, or undocked, somewhere in the middle of your page. If it's the latter, drag it to the bottom of your window to dock it.
Then on the Drawing toolbar select "Line" - looks a bit like this \
Now when you rest your cursor over the body of the document, it will look like a plus symbol. Click and drag in any direction and a line will be drawn (BTW - double clicking line leaves lines switched on, single clicking does just one line). You can then click the line and change it's direction, length, thickness, colour etc or delete it at will.
By default, the "Snap to Grid" function is switched on, which forces your drawn lines to be positioned in increments. This function can be used to force the right-hand end of your lines to be justified, however, you may find that they don't sit quite right next to the text - i.e. they may only sit a little too high or low on the line, or not close enough to the text. If this is the case, get the right hand edges correct first, then go to "Draw" on the Drawing toolbar, and click "Grid...". In the box that appears, remove the check-mark from "Snap to Grid", OK.
Then you will be able to move and resize the lines to your requirements.
Increase the zoom if necessary to get them just right.
HTH
Gram