Thank you all so much for your replies

He certainly knows I'm not ftm (although I remember someone actually thinking that once while I was in the thick of my transition). He's a really nice guy so I don't think he's being intentionally rude and it's something new now after I told him about me. He never said anything like that before and we have been chatting online for about a year and a half. I'm almost getting the feeling he doesn't even know he's doing it, which in some ways I find even more disturbing than someone doing it on purpose, hence todays sudden paranoia and loss of self-confidence

I was actually quiet upset earlier today. Luckily I have a wonderful husband that comforted me, but even after all this time we've spent together (had our 6 year anniversary just last week, hehe) it's difficult for him to understand exactly how and why this sort of thing bothers me so much. I've had friends that changed their name, but only for the reason that they didn't like their name. At first it's easy to get it wrong, as happened a lot with both name and pronouns during transition (especially early on). But unlike the friend that got annoyed when I would forget to use their new name it goes so much deeper for us that are trans, yet most people seem to think the two situations (the friend with the new name and us with the new pronoun) are somehow the same.
My friends and family would get it wrong occasionally even after as much as 1 1/2 years into transition! I would often times get visibly upset and they would smooth over it by telling me how ingrained the male pronoun was and how hard it was to remember to get it right every time. They were completely clueless to the root cause of me being upset. It wasn't so much hearing the wrong pronoun that bothered me so much but rather the suspicion that the times they got it right was all an act on their part. My true resentment was not aimed at them but rather towards myself for possibly not succeeding in reaching my goals.
I think the hardest part of transition was the fear and uncertainty of whether things would turn out okay or not in the end, and then to have friends and family pretty much confirm they were just humoring me....well, it was not a good feeling. Total paranoia. To this day I still don't think anyone actually understood how this all made me feel. Even my husband seem to miss the point whenever I try to explain it so maybe it's on of those things that has to be experienced to be understood.
In the end though things turned out okay though. I reached my goal and I know that the people around me now truly see me for who I am. The fact of the mater is that they never ever get it wrong anymore simply because they are no longer try, they just do. Today however, when my friend start referring to me with the equivalent of "dude" and "buddy" all of a sudden, it takes me right back to the miserable place I was in way back then and that is why I find the seeming no intention of it so disturbing.