#divorce

I am having a hard time communicating with my 6yo son. Help!

I am having a very hard time with my 6yo son. As soon as he sees me he looks disappointed, gets angry with me, talks to me in a bad manner, starts acting up, and doing things that he knows he is not supposed to do. His brother tells me that he doesn’t do that with dad and at his house he does what he is told. I have had a lot of stress at work and with personal matters so I struggle sometimes to stay in the moment and be as fun as dad is. I try to talk to him and have patience but it gets to a point where I explode because he is just not listening to me and keeps escalating the situation. I tell him to stop several times, his brother does too and he keeps going.
Please remind me when he talks to me in a mad manner or screams at me what is the best way to handle.

How detailed should the divorce conversation be with children?

The kids were asking me the other day about dad not living in the house and us being separated. I told them the same thing I always say, that we are better people and parents this way. Then they asked who left first. I paused and just said what we had told them originally.
Later, it got me thinking if that was the best approach. I think they blame me for the whole thing so part of me wants to tell them exactly what happened. Is that wise?

How can I help my son have a better relationship with his dad?

In my son's transition from one school to another, his relationship with his Dad has deteriorated. 
My son refused to go to his home, see him or talk to him.  When forced, he engaged in fight or flight, refused to eat, yelled and refused to come out of his room at his dads. 
Dad has allowed him to stay with me for the last three weeks, hoping that giving him time would help. I am at a loss how to help them with this relationship or at least get my son to the table. Please help!  I'll pass on the tips. Thank you!