First of all, you do not need to feel guilty about reading commentaries and other sources on the text of the Bible.  I feel myself to be in the same position as you at times.  I have read Romans so many times, that sometimes I feel I get more out of Romans by reading commentaries on the book than by reading the book itself.  I am somewhat embarrassed to admit that sometimes when I read the commentaries, I skip the reading of the text itself (because I am so familiar), and skip right to the comments! You do not need to feel that you are sinning or even making a big mistake here.

However, you have a sense that it is important to stay true to the text and to receive inspiration in your life from the text itself.  After all, it is the original which is “living and active” and which can “judge the thoughts and attitudes of the heart,” (Hebrews 4:12) not commentaries.  My admonition is that you remember this fact, and that you discipline yourself to spend time in the original when you use other sources. Do not follow my bad example, mentioned above! You should read and even be inspired by commentators and the like, but form the discipline to continue regular reading of the texts themselves, even if you do not feel particularly inspired on one occasion or another.  Also, when you use commentaries, discipline yourself to pay attention to the text as much as you do to the comments on the text.  If you do this, you should be just fine.

John Oakes