I’m not sure you are really upset about the vasectomy so much as upset about the fact he didn’t communicate with you, when usually you think he would have. It sounds out of character, so perhaps he felt certain he didn’t want more kids and he didn’t want you to accidentally fall pregnant nor did he want to force you to make a decision and wanted to be responsible.
It sounds like now he is back pedalling, suggesting a reversal to appease you. Which is a bit crazy in my opinion, if neither of you really want more kids!
So it is decision time - Would you have supported the decision, if you had time to talk to him about it before hand? Ultimately if you would have supported his right to decide to have the vasectomy, then you need to let go of your anger and forgive him.
And then decide together DO you want more kids, because there is no point reversing a vasectomy if you don’t.
He knows he did the wrong thing by doing this alone, emphasise you want to share thoughts and decisions especially when they are important and difficult. Then move on. This isn’t something to end a relationship over.
Ps I have overheard (at work) blokes discussing their vasectomies and it does seem to be something most men take pretty seriously, although they may appear to joke around a bit, it is a big step and they seem to get some kind of validation from talking about it amongst other men. So I would definitely not make an issue of that either.