@Strawberryhill It's really better if you start a new thread.
I'm sorry you are having such a hard time. I'm going to address your post just from a legal perspective. It has little to do with what the right or wrong thing to do is from a good manners approach. My experience is when things start getting vitriolic there is usually some behavior that can be changed on your part that may be contributing. Remember you can never control the other person. You must rise above the pettiness. Show you are reasonable. Be respectful. Don't make demands that are not outlined in the decree. Even if they are outlined in the decree do your best to give the other party every opportunity to do the right thing.
There are no easy answers for post divorce life. It's a transition and a journey. The experiences you had with your Ex while you were married and immediately post divorce are going to be very different than the experiences you have yet to have. Your Ex has decided to make room in his life for another partner. With that change comes very BIG changes for everyone around him including you. Overall as long as the kids are not in danger- his life and his partner choices are not really any of your concern.
There must be some reason for the chillier temperatures. There always is. Are you being insistent that he respond? Are you overstepping a boundary? Ex's of all flavors tend to have the same expectations of post divorce communication as they did during the marriage and the divorce. That extends to rude treatment. If you ever watch how a husband and wife sometimes talk to each other it can be painful to listen to. The level of rudeness goes beyond anything they would do to a co-worker or casual friend. But because that person was an intimate partner there is this familiarity and rudeness that can creep in. Make sure you are not doing that. Treat him and his choice of partner with respect and you should get respect back in kind. Record your next few conversations with him and listen to how you guys sound. If you don't sound like you are in a business meeting with a slight bit of friendliness thrown in you are doing it the wrong way.
But you got divorced for a reason. He doesn't really owe you anything short of kid related issues. He does not need to be friends with you. If you showed any kind of disrespect towards him and his new partner you can expect to be treated like this. Women can be territorial and the new woman is bound to have some insecurities with regard to you. If you want to make headway and actually meet her one day show a lot of deference and respect towards his choices. Respect any requests he has made of you regarding your communication. That will get you further than demands.
You only have a right to insure your children are not in danger. Unless there is some sort of paramour clause in your decree your Ex has the right to date whomever he wishes and he does not have to tell you. You can start documenting abnormal things you observe or hear about from your kids if it makes you feel better. If something is amiss than the documentation will serve you well in the future.
My advice to you coming from a place of dealing with an extremely high conflict divorce situation is to do everything in your power to get along and be respectful. Our next round of court battles will likely drive our cost up close to $40,000. I kid you not. And it's all because the Ex is pissed she can no longer control her Ex husband. She has super rich parents who are willing to bankroll her attacks.
Just don't go there. It's not worth it for you or your 11 year old son. Move on with your own life. You will very likely get to meet his new partner one day. Best it be on good terms rather than hateful ones. If your case does get reopened and you end up back in court, ask for both of you to start using My Family Wizard. That email/communication program helps keeps lots of families on track for communicating respectfully and in a timely manner.
Best of Luck!