I think you are doing very well and yes, you will know your child. The fact you have been able to discuss with your child and explain the difference between "stupid behaviour" and being called "stupid" speaks volumes for your emotional intelligence.
The things you have been told by other parents who have personally heard words they are uncomfortable with, other children and your own child are definitely all things that cause me concern.
You are taking care of your child in this situation by discussing as you have, that's really good.
The teacher should not have come on the phone with you, you had a concern and a professional teacher would have arranged for this to be dealt with properly i.e. a conversation in person including their supervisor. As a teacher, if children are saying things that feel are unfair or untrue, it is the teacher's responsibility to take this on and deal with it, both for the child or children involved (are they misunderstanding, is there upset for other reasons, how can this be resolved so that children are comfortable and understand) as well as own professional reputation (if it was suggested I did something didn't or something was taken out of context, I would want that discussed and understanding reached for myself!). So the teacher's behaviour towards you concerns me too.
It is good that other parents are in the conversation with you, I would definitely want them to stay a part of this so I didn't somehow end up getting sent in on my own. Plus if other children/parents are raising concerns, it's not just an issue about one child, it's a community issue.
So, you are doing well.
Yes I would continue with the meeting, take someone else with you, maybe another parent and someone without a child at the school who can witness the conversation, if possible. If nothing is done (there should always be a formal response) or you feel patronised or dismissed, absolutely keep going up the ladder and keep the other parents with you. I'd try to avoid taking it on alone or being the spokesperson as in general this can lead to things being made personal about you as a distraction.
Stay calm and keep doing what you are doing with your child, I think you are doing really well.