Steve and LoneWlf, thanks so much for your responses.
Steve, good catch about D3, yes all this was right in front of her. In my efforts to validate and stay calm, I did not enforce my boundaries of no D talk in front of D3 and D talks only at certain times and he threw them right out the door.
He has never been disrespectful in the 15 years before, has always been loving and supportive. I always thought he is the most patient person until BD when I realized he was a dormant volcano that was building up inside in a unhealthy way. Since BD he has been angry, bitter, condescending and disrespectful.
And swearing in front of kids is just not how he was before.

I need to learn to combine aspects of staying calm, validating and enforcing my boundaries

Originally Posted By: LoneWlf
when he starts swearing at you that is highly disrespectful and in my opinion the conversation ends right there. I would simply state to him that you are not comfortable with his ton

I keep giving him credit for who he was before the BD and try telling myself he is in a bad place and I need to be patient. But I need to stand my ground and stop buckling under pressure. I will definitely work on that, thanks LoneWlf.