Hard, of course I won't kill you.

I appreciate you, your whole post and your insight to realize how invalidating it is to Fe-shut-people up. The extroverted judging function does feel it is in the right! But here's the difference, you and I could battle it out, I would take you on and we could go toe-to-toe (although I am at a natural disadvantage). But if it was important enough to us both, we would sort it out! From your vantage point, why can't it get sorted out in INFP-INFJ-land?
(And as an aside, how Fi sounds to you just makes me want to cry lol. First, because I think I expressed myself sincerely and eloquently, and second, because "me, me, me" is not the locus of my life. Being in second, third, fourth place is very familiar in caring for my family and friends and giving to other concerns. So, to articulate that out loud, putting me "first" is so huge to me, to speak to my individuality is such a big deal, for it to be called a lack of tact is pretty horrible to read actually.)
Well, here's how I look at this. Everyone has a variety of motives for expression at any given time. It's not that I don't see them, but I don't place much faith in motives, because I see a whole bunch that just have higher and lower probabilities and some that are in conflict or alignment with each other. (eta: this could be partly a social-dominant thing, I'm not sure all INFPs would agree with seeing that stuff.) To me, it's not necessary to hard-boil it to one because there's a bunch of possibilities, so I orient myself to a certain action both taking them into account and regardless of their existence. I place more faith in the internal read I guess. Which leads me to this:
I do see your point and I think you've likely hit this straight, and I myself have freely admitted I can sound holier-than-thou. But here's the rub: how do you show value when what value you have is internal and kind of hidden? I tried opening all that up, showing the inside (which isn't that pretty really at times) and it didn't help? I can just choose to live my life as an expression of my values and remain silent. (Actions speak louder than words and all.) But we're here on the forum and all we have is words. So how do I even build a tower when those blocks are invisible to the other party? I have no interest in knocking down INFJ blocks either, but I see some of the issues in what they are building and I can't help but point them out. Don't people want to know? I sure want to know when I'm building something inefficiently, even if having it pointed out smarts.
So if you can help me cut to the chase, throw out these stumbling blocks when dealing with INFJs, I'd appreciate it. And I've tried just doing Fe speak, it doesn't work because I can't keep it up forever, the Fi pokes out.
From what I have observed two introverts in an argument of some sort persists for much longer than it would with a I/E paring, and even longer than a E/E paring. This might sound sorta rude, but extroverts generally are better communicators, are faster at it, and hold back less. Because of INFP's need for privacy and guarding, and the INFJ's need for tact and careful wording, there ends up being a lot left unsaid, and when it is said it is said at the wrong moments. It's sort of like a communication breakdown. While INFJ's have a "let's get to the point" mentality, they're easily distracted. INFP's don't often need a point of sorts (discussion is enough). It can just keep going endlessly. Often resulting in either party going "Ok, I'm done..." Then one later coming up and saying "Wait, I thought about something, now I have this to say".
AWW! Please don't cry! I really need to make the distinctions here. I know when you open up like that (or Fi's in general) it's very vulnerable and raw. I don't think I was careful enough with how I explained that. You didn't use tact, but that's ok, and in fact using it would be improper. Doing so would completely defeat the purpose and reasons behind your actions. And tact; well that's a beast of its own. It can be a double edged sword because it requires a lot of self-censoring (and is the reason for a great deal of my emotional suppression). At it's worst it can make someone a bald faced liar.
(I'm gonna be referencing motives here a lot which I know you don't put a premium on, I will get to those in a bit) Here's why I reacted the way I did, and this could be used as a sort of example for Fe/Ni and Ni/Fe reaction to this sort of thing. It's actually stemming from the fact that you never put yourself first. That's actually assumed before even reading the full post and is just gathered from the person (and I have sensed that about you). As you said, it's the reason and why behind it all. For once, you want to and have to put yourself first and take a stand. Fe will say "well, what's
better is if you put yourself first more often, then this wouldn't have to happen period! Stop being a pushover/pincushion and be selfish!". Is that fair/right to you?
No. Fe reacts that way because it wants personal efficiency. It takes issue with the behavior only slightly because of the perceived "me" aspect. The big issue it takes is with the reasons/events that caused it in the first place. If that could be "fixed" then it would solve the whole situation. I see this sort of thing happen a lot when I see INFP/INFJ spats happen. The INFJ will get pricked because it's seeing the INFP as "screwing up" beforehand, and not doing anything about it. Not taking into account that this is how they opperate. Further, that they're getting shut down over and over form being able to put themselves first.
Ultimately though, I was aware of the fact that how I reacted initially is not fair. Under normal circumstances I flat out don't mention it as it's not important and would just upset the other party. The reason I brought it up now is because it's highly relevant for the discussion. Fe is judgemental of motives, but also does not run off internal reactions. If it feels an internal reaction, and it doesn't align with motive or intent, then it's disregarded. Anyway I'm starting to digress from the topic at hand. I will close this part by saying: I had an reaction, dismissed it as wrong/unfair, sought to understand the intent and drive, determined it to be very respectable and honest and thus it is to be valued, and ultimately good. Under normal circumstances pre-processing does not come out. I understand, and would not for a second dismiss you for doing so, if anything, that's something I'd hug the person over for what they've done and where they're coming from. I know for Fi this can feel very icky and dishonest, but remember that Fe works on the external.
As for how to speak to others better... I sadly do not have an answer. What I could offer would be meerly what I have learned to do and how I manage, which most don't understand or flat out dislike. I'd also venture to guess it would be completely counter to how you would operate and would actually be detrimental. That said, [MENTION=4945]EJCC[/MENTION] offers fantastic insight into how to go about this. Generally speaking, if you are helping someone, it's best to adapt to them so they can best absorb what is being taught. If you help another, indeed the focus has to be on the other, and the self needs to be avoided. Going into a "you're so ungreatful!" mode will completely push away the Fe user as it does not tollerate guilt triping at all.
I wouldn't worry so much of doing Fe-speak. That's not fair to ask yourself to do that anyway. I somewhat disagree with EJCC's assertion that it's either blame or adapt as I don't think it's so much binary. In particular for an INFP that could lead to them going way too far to one extreme or the other. I think something that would be helpful is for either side to consider how they deal with information. For INFP's, try and view things from a motives and purpose standpoint. For them it's not important, but INFJ's use this a good amount, if that's thought about some, it could aid in more mutual ground. For INFJ's to recognize that sometimes, there is no between-the-lines reading, and to realize that an INFP is going to self and internal reference. Don't disregard it or them. I know that might not be as substanting as you'd like, but I don't think there is as clear cut of an answer. I'm also not the best at generalizing in this sort of manner. I'm more case-by-case.