Maybe you smoked too much? You have a very low tolerance since you've been sober 20 years. One puff, and you should be done for the night. I sometimes think bad thoughts when I'm TOO high. It's like the saying, 'too much of a good thing, can be a bad thing'. MJ is powerful stuff.
You said that you've actually had these feelings before, but they're not actual facts... did you used to get these thoughts when you smoked before? Like I said in my first post, I think MJ surfaces thoughts we've suppressed, and it seems you've noticed that too. It makes me wonder if you feel good about yourself. Do you? Maybe it was because you smoked during a stressful period in your life (religion/belief issues)? You need to be in a positive mood if you want MJ to be a pleasurable experience in my opinion.
The cleansing should help. It'll clear your mind, and lift your spirits... so maybe you'll have a better experience next time.