When you first tell people around you about your genderdisphoria and your transition, it takes a certain while for them to sink in. For most of them, this comes as a genuine shock as they've been completely oblivious to what was going on inside of you all this time . You've already come a very long way when you first tell them, whereas they're just now able to see you for the beautiful girl you really are. They inevitably wonder what this revelation means to them, because they've constructed an image on you based on their perception of you, and now they are confronted with the fact that this image they have so carefully construed is no longer correct.
It may take them a day, a week, a month or longer, or they may never come around to it. Sensible people, however, eventually realise that it's YOU that matters, and not them. In certain instances, however, they don't make that realisation. They are, in a manner of speaking, not able to get over themselves. Your transition places them in such a position that they are unable to cope with it. They're not doing it consciously or deliberately - it's just that they simply cannot get their thick head around it.
I.e. the two friends who made the comment that what mattered was that you were still the same person on the inside, I don't know... To me (and, mind you, I'm the significant other of a MtF, so not transgendered myself) this comes across as if they're clinging to the image they've construed of you. Sounds to me like they're basically saying: "you're still the same person on the inside that we once perceived on the outside". That's not really accepting.
Basically, what it boils down to is that, for them, "they" are more important than "you" - except that to call it like this is way too crude. It's much subtler, as often they don't realise it themselves. In most cases, they believe they're genuinly trying, but don't realise they don't actually succeed. They delude themselves into thinking they're doing the best they can - but the thing is, they're really not. Mostly, it's these people that will complain about how hard it is for them and how complicated things are, while making no mention of the fact that it is YOU that is going through all this and that's it's harder for you than anyone of them. That's because, mostly, it doesn't even occur to them.
Do you need people like this? I'm sure you don't. Don't get me wrong. People make mistakes. They slip up sometimes. There may not be anything behind it. You've invested too much time and effort in these friendships to simply burn the bridges. If, however, you've shown patience and consideration while they try and they keep making these mistakes, they're obviously not trying hard enough to understand, accept and support you. Winding yourself up and correcting them every time, only for them to slip up once more and then act as if it's no big deal really puts an emotional drain on you. If that is the case, your relationship/friendship with them is unbalanced. They mostly take, and you give, whereas they give you less in return.
We all want need people around us that accept us for who we are and that are supportive of us. If your friends aren't supportive or acceptive enough, they're the ones to blame - not you. Perhaps, then, it is time to learn to know new people.