Hi everyone. Don't feel quite strong enough for AIBU at the moment, so hope you won't mind me posting this here! Would like to get others' perspectives on it.
A bit of backstory: split with my ex husband and father of my children, after repeated infidelity was revealed. He now lives with the o/w and the children live full-time with me (other than a fortnightly overnight stay). He has always been a strong character, arrogant some might say. Not a bad person, and a great dad, but his attitude towards me can be strange. We are seldom together these days, but when we are (e.g. Christmas) he will talk down to me, undermined me in front of the children, can barely stand to look at me. Have now started to cry as I type this 
He makes me feel like an employee that doesn't pull their weight, and he is the line manager! Not like equals at all, and he can be rather disdainful. This isn't helped by the fact that he is very successful in his career, earns a very high salary, and I am at home. I realise this isn't the ideal situation, to be financially independent on him, so am booked on a course for women returning to work. I am trying to get my life back together.
It used to be that his attitude towards me really affected my moods, but I have come some way in moving past this, and try hard to be more resilient.
So today he has our youngest two, and I am home with our teenager who is ill.
I just received a very abrupt text from him (no hello or anything) asking when the children were last at the dentist.
I replied that I couldn't remember, but could make an appointment for them anytime, and asked if everything was ok.
He then asked if check-ups weren't a scheduled thing every 6 months (which is a fair point), and again asked when they were last there. He said that our 7 year old had a bit of plaque on her teeth (strange that he should be looking, when they're not even there overnight).
I thanked him for letting me know and said that I would phone the dentist tomorrow, to make check-up appointments.
He then asked yet again when they were last there 
My final text was to say that he had made his point, and that I was going to act on it, so please stop pressing it. I said that it was neither pleasant nor necessary. I added that neither child had even needed a filling up till this point, which is pretty good going (they are 10 and 7).
I know that this all sounds exceptionally trivial, but I guess it's all part of a bigger picture. I sometimes live on my nerves a bit with our exchanges, as I never know how he is going to be, or when I will next be pulled up over something.
It's just so hard, and I hate to think of having him in my life for the foreseeable future.
So, do I sound pathetic over the dentist thing, or can you understand where I am coming from?
Thanks in advance 