Also, I'm angry that they don't want the same relationship I want...I think this goes to the root of the issue. I want a threesome with some alone time for them on the side. They want a twosome with some time with me.
I've come to terms with that BUT the time with me is REALLY time for the two of them while I pick up the living room, fart around on the internet, and generally try to disappear into the woodwork.
Do I have a right to be upset about that? Am I being a bad primary and unsupportive?
You can feel whatever it is you feel. If you don't like how you are feeling, could change your behavior, see what new feelings ensue, and if that serves you better.
Since you did not sort out the relationship shape ahead of time...
- I want a threesome with some alone time for them on the side.
- They want a twosome with some time with me.
you got some upset/discomfort. I'm sorry it hit you like it did. Doesn't sound like fun to feel.
While accepting the shape
you still don't know how you fit in that shape or what is expected. "Some time with me" is WHAT? Once a week dinner and movie out together as friends? Something else?
How much public display of affection is ok with you and how much is too much to witness while this is still new?
WHEN are they seeing each other and what does that mean for you/kids? Are you always default babysitter or do you hire one sometimes so you too can get a night off parenting? Or do they babysit together while you go out to do something?
Could sort these detail things out so you can move it forward. Talk together. Make the plan for the next 3 mos, try it on, and then make whatever tweaks necessary. It's takes a while to find the "new normal."
If you come to find this is more than you can handle at this time -- could say so up front.