What I've quoted is some great phrasing on your part--and I find that it's very true. Frequently, I need a good Te/Si slap to the face. (Man I need to start dating an ISTp again...!)
As to what you wrote about SLI-Te's laughing w/ certain friend(s) while arguing w/ another--I've noticed this too. Begging the question, to Te types or any SLI: honestly, is this just a charade (i.e. you're laughing, but you're really hurting,) or are you really able to compartmentalize your lives to this degree? If the latter, then it's probably a blessing for the SLI, but a curse for anyone who might have to trust the SLI to be entirely open about their lives, (i.e. someone in a close relationship w/ him/her.)
I can't hide what I feel AT ALL--I suspect that it's like this for other ENFps..? It's all over my face, in my vocal inflections, and when I try to lie it's so damn obvious that other ppl have told me it's comical... It's a curse, haha!
As to the "none of your business" thing, I agree with that too; however, you're right, it's pretty natural, (in my experience anyway,) for an IEE to get an SLI to open up in such cases...
Thanks for sharing this--it's good info, and it's helping to increase my knowledge.