As someone who has a good relationship
with his ex, and wants to keep it that way, I second the advice to:
1) Don't go to your mom's. She and your brother can enjoy their pity-party "Coley's so mean! She won't let us see DS!"
2) Give your ex a supportive heads-up call. He probably gives in to your mom because he doesn't want to look like the bad guy in your DS's life. Tell him that you want
him to keep his time with your DS -- that that time is more important than DS seeing his grandmother on a particular date.
Definitely try the preemptive scheduling for next year. Revel in being the Scapegoat -- treat it as a badge of honor.
As a side-note: There are a couple of ways of working an amicable custody arrangement. One is to stick closely to the given schedule, which is what you're doing. My ex and I took the approach that, barring certain conflicts, we'll trade off when the other asks. Our base agreement is to switch every week, so things are equal to start with. That makes it easy for us to trade a few days or a week or two as needed. Neither approach is more "right" than the other -- I just wanted to point out a different way of looking at things -- I certainly wouldn't suggest any kind of a swap in this
She will pile on the guilt. In the past when I've declined to attend because of custody conflicts, I have been told that I am deliberately keeping DS away from his cousins because I won't rearrange the schedule. It's fascinating to me that when my brother declines an invitation because of a custody conflict, his situation is completely understood and the holiday is rescheduled.
Funny, isn't it? In the stereotype, it should be your ex pulling this manipulative garbage and your mom should be the flexible one. Sadly, her "mom" script is defective. Probably lost a couple of pages.
To help steel your spine - it's her
whose actions are preventing your DS from having a relationship
with her and (supposedly) with his cousins. If those relationships
were actually important to her, she
would find a way to facilitate them. Because she doesn't, it's clear that they're only important to her when she can use them to punish you. The guilt isn't about your son, it's about her controlling you
. He's just a convenient (and powerful) lever.