Advisor retirement while finishing doctorate on limited time constraint
The most promising strategy is to work with at least one committee member other than your advisor. The first choice may be the one that is a potential advisor, but you really need someone who is both approachable and good at academic politics.

Anyone like that is going to be very busy, and you need most of the meeting to be about them advising you and thinking of ways to improve the situation. You must strip your wall of text down to a few key points:


You are on a tight academic deadline, because credits will disappear if you do not graduate this year, and you will not be able to finish your PhD if you cannot meet the deadline.
Finishing the PhD is personally and financially important to you.
You proceeded with the research presented at your preliminary oral exam, which you thought had been approved.
You have been having trouble getting feedback from your advisor.
At your recent meeting, you had trouble communicating with him, and he seemed to be requiring a change in research line that would make completing the PhD impossible.


Two topics to not discuss: Your prior performance, and the advisor's personal issues. The professors should be dealing with the person you are now. What matters is your current difficulty with your advisor, not the reasons behind it.