No worries about being absent for a while. My own visits to the forums have been pretty sporadic of late, too, albeit for different reasons. It's understandable interaction is hard when you're feeling down - you are an introvert, after all.
Sorry to hear you've ran into some INFJs that turned out to be rude. Can I ask in what way they were rude? Sometimes behaviour can tell a bit about what lies beneath it - you may just have met them at a bad moment. Or life's little variables could be at play - types aren't as black and white as they may appear. One may err on the side of another, similar type, or simply have fallen into one or more of the potential negative spirals that any given type is prone to. Bear in mind that any individual can pursue or live up to their potential, or can conversely identify too closely with the pitfalls in their nature and go the other way instead. As a side note, have you considered that they may have even misidentified their personality types? It can happen now and then, especially if the information provided is not thoroughly examined. From the tests alone I could just as easily have come up as an INTJ (and have on some), but on closer inspection I most definitely identify as INTP... with one or two INTJ traits or leanings.
I'm afraid you misread my partner's type, he is an INTJ, not INFJ. I'm more than happy to share about how we relate to each other if you're still interested, though. We are very similar thinkers, but knowing the types has certainly helped demystify things when our respective approaches to logic clash or don't quite make sense to each other.
The best insights I can give you into my experience with an INFJ is a close friend of mine. You bet she's very sensitive, and self-conscious and struggles a lot with assertiveness. But she is also someone of great depth and sincerity, whom I have a lot of respect for. In terms of socialising, I think your intuition is your best friend. Because you're an introvert, interacting can be draining, and you don't want to waste your time on idiots. Observe people where you can, and you'll see for yourself who is worth interacting with. Where you see substance and depth, they will likely respond to those things in yourself, and that will be the basis of a solid friendship.