Going behind somebody's back to say untrue nasty shit to somebody and continuing to be nice to the victim, that's called 'gaslighting'. Narcassism is another thing by lacking empathy for the other person and enjoying somebody's pain.
If I were you, you better snap out of it. I've seen way worser shit and had dealt with this before so not a first. I've done plenty of research too on the matter so I know straight away what's up.
Your description has nothing to do with me. In fact, I feel almost offended. I simply make innocent jokes, as you do on the other hand. I am surprised by this reaction of yours. You should already know me a little, after several jokes made over the past few months.
I really never get jokes at all, I would like it if tone indicators were used in the near future because to me it sounds like what you've said to me means that I believe it.