There's a lot of text here, I do apologize. Many thanks to those who read it all and provide commentary.
Background: I have worked with my adviser for ~7 years now carrying out research with him in the field for many seasons, receiving my BS under his guidance, and TAing for him for several years until I decided to begin my MS with him. Early on, he had been having family issues and at a point near the beginning of my MS, he informed me he would be focusing less on work and more on his family due to his focus having destroyed his family. I took this as a passing phase as he had done before, but he has proven me wrong.
Overall Situation: My adviser currently has negative intentions to his students, the department, and the school. He does the bare minimum in courses- teaching ~1 class per quarter, showing up late, leaving early, is never in his office (I'm not exaggerating, he does not use his office. He arrives to campus, teaches, and leaves); has a very negative attitude with the department and school with never submitting forms or reports on time as well as not attending some department meetings (or commencement); and constantly sends emails to faculty and students informing them of how he is being screwed by the school (receiving reimbursements months later and having to deal with overdue bills and credit card charges). No students respect him within the department and his classes are the lowest rated to the point of being a joke. His reputation is so bad that when his next grad class is offered this coming winter, I feel it will be canceled because absolutely none of the students intend to enroll in it. Research-wise, he has been collecting data on a large project for ~15 years and has not published anything during that time. Currently the data and work sits and we are again in the middle of a summer when he intends to write something (this has been stated for each of the last 4 summers straight and it never happens).
My Situation: My thesis has gone no where. Meetings are constantly cancelled and put off by him, he has provided little to no literature (even then only broad background papers that he had me read for my BS), has shown no advancing interest in exploring ArcGIS with me to understand how to manipulate data. Some lunch meetings have taken place, over the past two years, but they end up being social and minor mentioning of work is as far as the conversation gets. The last two meetings I had with him were group meetings with 2 other students working with him (the other third already left for another project) and the meetings solely revolved around their projects and how I could help/guide them. Being roughly 6 months prior to graduation, I am currently assembling text and running analysis on data entirely on my own. Emails to meet and go over the process this week have gone unanswered.
Currently: Recent statements from other faculty and students are that in recent meetings my adviser has been using me as an example to state students need to submit 'final' drafts 6 months before defense. The department has a deadline of one month before defense for a completed 'first' draft. I am under the impression, given the past actions of my adviser, that he may be setting me up to make a point to the other faculty that 6 months beforehand is needed because he did not have proper time to read and review it. All of this would be fabricated from his own lack of meeting and involvement in my thesis writing. I am absolutely appalled at how he claim such expectations when he himself has put zero effort into the project whatsoever.
SO, with all that background, I sit here with ~20 pages of some spotty text and images and am very close to deciding, enough is enough, I would be better off dropping this project and ceasing work with him, and in turn picking up a project with another faculty member. I would rather spend a bit more time investing in a new project and doing that than finishing this and continuing to have to put up with his actions.
My question is, with what I have informed you of here, how do I do it? Also, along those lines, if I do decide to do this, would it be entirely unprofessional to inform the other grad student who just started up her project to drop it and go to another adviser? (She has already commented I have been more of an adviser to her providing background readings, information, and 100s of Mbs worth of unprocessed data for her project...)