Email and conflict are a bad combination. Nine times out of ten, email fuels conflict when it is present rather than defuses it. We write things we would not say in person and there is no opportunity for the one we are writing to too see our face, hear our tone or read our body language. Email and conflict are incompatible. It is the shadow side of technology! Somehow it is easier to judge motives and make assumptions when we are not face to face than when we are.
I confess to being reactive at times on email in a way that I didn't like and was not helpful to the situation. I have a personal saying that I remind myself of often, KMS (Keep Mouth Shut) which has served me well. I add to that DHS (Don't Hit Send) when it comes to email in conflictual situations. I know from experience it will not help and will probably hurt. Like you I have paid dumb tax on this one.
When tempted to send an email in a conflictual situation my advice is to first wait 24 hours before writing and then to have a trusted friend or colleague read it before hitting send. My best advice is to not engage in conflict via email at all but to send a short reply that says, "Thanks for sharing your concerns, lets find a time to talk by phone or in person."
For some reason, we are all more reasonable in person than in email. And emails don't go away. In fact they are often passed on to others who we would not want them shared with. Don't put in writing what you don't want others to see. Emails escalate while face to face conversations with reasonable people generally deescalate.
In conflict, DHS. Instead pick up the phone and talk. Things will go much better.