Thanks so much for replying.
-We've talked a lot about my potentially having kids. He has confirmed that yes, he would absolutely want to have children with me if that's what I want. And S has also said this is ok, but it was a while ago that it was discussed. But it's 3 years minimum down the road for me as I will be back in school soon.
-I'm technically free to date others. I haven't closed that door for myself completely, but I'm honestly 0% interested. Maybe I'll meet someone, but I'm not looking. Except for dealing with the complications of the setup, he does meet nearly all of my needs.
-Happy and troubled. Yes it did cross a line, and totally shifted my thinking about this entire thing. But it also gives me some comfort and security to know that I still have a unique importance to him.
-I was definitely pissed off that they did this without discussing their plans. I know that they're technically "allowed" to do this but it seems disrespectful and hurtful to not even talk about how it would affect me/us. I've told him that communication absolutely needs to improve and that if they say they want me to be a part of the family... that's part of it.
I know that the beginning sounds bad. This is basically what I mean when I say "not how poly is supposed to be." As in starting when he fell into it mostly against his will to do what his wife wanted, and I fell into it because I fell in love with him (not the poly situation).
What I want is to actually feel like an equal. If I have to make the best of a less-than-ideal situation, I would rather have my metamour happy to see her husband happy instead of complain that they don't have what we have. If I'm going to be somewhat of a co-parent and adult figure to the kids to the best of my ability, I want to feel more integrated into the family. And I also want some more independence in my relationship with D, because I do need that. I also have all the expected selfish worries about time/scheduling/attention when my one-and-only is married with a toddler and an infant. There isn't really a way to work on that part except me knowing that he's such a badass dad, and I'm pretty good with kids, that it'll probably work out in the end even though it keeps me up at night now.
So basically... I'm choosing to continue to participate because I can't imagine my life without him at this point. Sometimes I wish things were different, but also remind myself that I fell in love with him as a whole person, including what an amazing partner and father he is. I just don't want to always feel like I'm always begging/hoping for more time and that I'm taking away from what he already has, which is how she makes me feel sometimes.