If you haven't already, you should start a thread for your situation. That way people know where to find you and can help.
First, if you are dealing with any depression issues, get to a C. I also hear a lot of negative thinking in your post. She and/or the stress "beat you down." There is a great book that can help you change the way you think about and handle these stressors - "Learned Optimism" by Martin Seligman. Give it a read. Can only help.
Second, from what you say, I wonder if you made "changes" for you or to keep from getting D'd. The changes MUST be for you, and ONLY YOU. Otherwise, they won't stick and she won't believe them.
Third, it sounds like you need a frank discussion with your W about assigning blame. Don't be accusatory or tell her how she is wrong. Just tell her you hear her, you understand, but that while you may partially (50%) to blame for certain things, it is not all your fault. Specifically, accept and own your 50% (no more, no less) part of the reason your M is where it is. And if she reverts to telling you something is 100% your fault when it isn't, just tell her you are sorry she feels that way, but that simply isn't true. Acknowledge your part, then leave it.
Really examine where where you need to change for YOU. Then be consistent.
