Let your utterances be gracious...seasoned with salt. (old proverb)
(salt is not only for flavor it's also a preservative and keeps things suitible for eating...)
I think in my head of many things I could say...alot of them would be cutting..what's the point unless it's someone who is being a complete jerk...and even then it's not worth it sometimes people like that seldom ever think they are wrong and it's pointless to argue with them....(lots of examples of this on this forum...and from all the types) Someone said once on here that they've never heard me say anything mean to anyone on the forum...I've definately thought it...BIG TIME...and if I feel strongly enough about something I'll say it...tactfully but definately with force so they get the point. People generally can't handle when I don't censor myself because usually it's very pointed and it usually ends the convo.
Your friend who says it's inconsiderate to not pay attention to your words and who you say them to is correct (in my book and maybe it's an ENFJ thing) Perhaps it's not that she can't catch up with your thoughts...maybe she's with and beyond your thinking in terms of she gets it..she gets it a joke but she's thinking about how your words "could" be construed.
It's hard to censor yourself for oversenstive people...it's alot easier to just say what you want and tell people to get over it.