I agree that the tape recording could get you in trouble. Also depending on your workplace policy on social media, any comments about work (especially negative ones) could spell trouble. (My hubby's workplace specifically prohibits any workplace stuff appearing on social media. Penalty is losing the job, no explanations accepted. You post work drama on facebook or other media, you are fired.)
I would tread lightly in this area, for sure. Saving emails, certainly. Those are records in writing that do not go away. But always i would remember that the same can go for myself. I always keep it in the back of my mind that anything i put on the internet, on any forum, could be viewed by any number of ppl. I try to keep it vague and mostly nice or at least not too mean.
Ppl have the right to run their mouths. They have the right to be stupid. Unfortunately good ppl have to deal with stupid ppl at times. I would keep stuff that is in writing, such as emails and memos, if you think you will need it. You are not obligated to disclose that you are an aspie, as far as i know. (unless you have already done so, then i guess it isn't like you can take it back.)
Other than that, i would do my job and do it well. Let him have his opinion (you don't have to agree), but be the best worker you can be. Often if someone is really a jerk, they will dig their own grave. But if you get sucked into drama, they may take you down with them. Then you have not gained anything. Keep it classy on your part. That would be my advice.