I'm sorry I didn't read this earlier. I 100% agree with lavendersage. It doesn't matter whether his particular case of ADHD is related to that behaviour or not. Nothing makes that kind of behaviour okay. Nothing you did could possibly merit a response like that from another person. Someone capable of behaving like that should not be a part of your and your children's lives.

The kind of person you want to be with can take being snapped at (especially when it's obviously got nothing to do with them) without getting defensive or angry, but simply ask what's wrong and try to help you feel better. They'd empathize with your feelings at least a little. Ideally, they might even try to do something to cheer you and the kids up. It doesn't matter what kind of "good side" he has. That man is dangerous.