It might be best to simply move the Reply button say, all the way to the right so that you do not accidentally click it, but also so that it is there if you need it.

You can do this by right clicking on the toolbar, choose Customize Ribbon. Rename the "Respond" group to something else, say "Respond (orig)". Then create a New Group, call it say, "My Response" and copy the Forward command from the left hand pane over to it (plus any other commands you normally use):


Hope this helps!