How would you feel if that teacher brought up random gossip she may have heard about you at a conference, information that has nothing to do with your child's education? If the situation were reversed, I'm betting you would be completely indignant- and rightfully so. I don't really understand why teachers aren't also deserving of basic etiquette in their interactions with parents.
If the teacher wasn't following the IEP, yes, that's an ENORMOUS problem. Any other issue is completely secondary. I think it is a massive assumption to think that the teacher in question had all this free time to pursue specialized training- this is an administrative issue to the highest degree. Teachers get stupid assignments from administrators all the time that don't match their qualifications, right or wrong. Even after voicing their grave concerns and ethics about such circumstances, teachers have no power to do anything about that, other than try as hard as they can to do right by those students. Should this teacher have done better? Possibly, probably- I wasn't there- but I don't think that gives you the right to pull random, secondhand heresay about her career goals into that conversation. That is, frankly, none of your business and has no bearing on the teacher's performance (or lack of performance) in the classroom with your child. Just because she had to be professional and not respond to that personal attack in kind doesn't make it right that you did that. I have never met a teacher who aspired to utilize their students as guinea pigs in their quest to climb the career ladder. Actually, there's not much of a ladder to climb in education, as much as it may be a lateral transfer of sorts.
You are justified - encouraged, even- to fight for your child's education and well-being, of course, but I think that throwing gossip in the teacher's face about her career aspirations, whether true or not, was completely out of line. That is completely irrelevant- the only issue that should have been addressed in your conference was the quality of education your own child is- or is not- receiving. The teacher really doesn't have to answer to you in any other vein than that concerning your child. Period.
I'm tired of the level of disrespect that occurs toward teachers on a regular basis that is deemed acceptable in some circles. You can be an advocate for your child without dragging the teacher's personal business into the mix. The profession loses a lot of excellent teachers who tire of being in a position of weathering awful verbal abuse at times from parents, and cannot say anything on that level in return. I used to teach high school and weathered my share of inappropriate observations from parents. One of the perks of being a college professor now is that I no longer have to interact with those types of parents.
Parents and teachers must work TOGETHER, not against each other. It's a two-way street. I doubt that teacher wants to have any further interactions with you, and would likely take great pains to avoid you, even. I think it's best to move on and try really hard to stay professional in the future. Keep the focus on your child and you will get the best results in return.