If memory serves, it was some sort of course that the OP didn't want to have to catch up on having missed a session.
It's interesting that she needs to be at home all the time because her 15 year old mustn't take public transport to school, but when the kid is actually ill, she mustn't be inconvenienced.
So I don't see why I should change when I am not the one who did wrong. If OH wasn't happy with the set up he should of said rather than seeking comfort elsewhere.
Neglecting your partner and treating them like a bank/domestic drudge/sexual servicer, is doing wrong. An affair is never right, but I wouldn't feel much loyalty to a man who refused to sleep with me for years on end and, more importantly, refused to acknowledge that it was a legitimate issue for me. Why is it only that vow that people care about? What about 'to have and to hold, to love and to cherish'?
I'll bet a pound to a penny he tried to talk about it many times but when you continually made it clear that you didn't give a shit about him as long as he was bankrolling you, he just gave up asking because he knew it was pointless.
To answer your question, yes, you are being very unreasonable.