Like others on here, I have been dealing with this type of stuff for several years.
My conclusion, which others may dispute, is pretty simple: you need to focus on being a good parent. It's nothing more complicated than that (although, being a good parent is complicated). Being a parent is not be their buddy or their friend -- it's different.
You are painting your STBXH as a classic Disney Dad. He's fun and exciting but he's not doing any parenting. If this is true, then your kids will eventually learn to dislike him for that.
Anyway, back to you:
(1) it sounds like you need to focus more on being a grey rock. I would not recommend that you have phone conversations with your ex. HOWEVER, if you are going to do so and he is going to verbally abuse you, then you should think about recording these conversations (check your laws to see if they allow one-party consent or two-party consent; I just checked the internet and it appears in Michigan that you can record any conversation in which you are a participant). You should absolutely hang up the phone if he is yelling at you and disparaging you and you are not recording it.
(2) I agree with others that you should not excessively compliment Disney Dad in front of your children. At the same time, you should never disparage him. I encourage my children to behave for their mother. If they are doing something with their mother, I say things like "I hope that you have a good time." I focus most of what I say on my children. I mostly avoid the topic of their mother.
(3) You need to be calm, steady, and reliable to counter-balance the crazy that they get with their father. The roller coasters that you experience with him? Unfortunately, they will get those too. You need to set your boundaries with your kids and you need to enforce them consistently and without a lot of emotion. You need to give your kids a life of boring, normal, and calm.
(4) You need to think about the long game. He might win these early (you aren't even divorced yet!), little, crazy battles but you need to think about winning the long-term, overall war (i.e., until they are adults -- and beyond!). Part of this is what I said in #3 -- creating a safe space for your kids to be kids is what they need.
The other thing that you need to consider is that being a Disney Dad is very difficult to keep up over the long term. If he is as narcissistic as you say, then he won't keep it up. It's time-consuming, it's expensive, and honestly... it's freaking difficult. I live near a reasonable amusement park with roller coasters, a water park, etc. They have a very reasonably-priced season pass, so I got season passes for me and for my children. I rarely plan any activities with my kids for the weekends that I have them; instead, I ask "hey, what do you want to do?" My 10 year-old likes to go to the amusement park. It's sooooo exhausting and painful (vertigo, anyone?) to ride roller coasters all weekend, every weekend at the age of 45-50 years. I've done this for the last two summers and I'll probably do it for the next 2-3 summers. It sucks personally, but it's awesome parenting time. A narcissist wouldn't be able to do something like that. And when that happens, the kids will notice: Dad, why don't we go to the amusement park anymore?
So, in summary: (a) Keep grey rocking; maybe even improve your grey rocking, (b) focus on being the best parent that you can be to your children, whatever that means to you, and (c) be patient and let Disney Dad try to keep it up. He'll either quit it (because it's hard) or... in the unlikely event that he keeps doing this stuff long-term... then you need to consider that he's actually being a decent father and you should be happy about that.
edited to add:
Um..no. You get every 3rd and 5th weekend? You mean that 5th weekend which is a rarity?
No.
No court will enforce this. Divorce and visitation aren't always convenient. If that means he needs to rearrange his schedule, or find a different job,then that's his problem. Not yours. There is no way you should be accommodating this bullshit.
Tell your attorney you want every other weekend.
This. 100% this. ALSO.
[This message edited by barcher144 at 9:26 PM, Monday, September 12th]