I'm sorry you are being treated this way. I'm in a triad with my husband and my girlfriend. We are not a vee, but a triangle. I think that is the key to how our relationship works. Given that he and I have been married for 10 years and she has been with us for a year it can be a struggle to make sure she is always included, but it gets easier all the time.
The relationship I have with her is great. One thing is that she dated only women before us, so she comes at this without the expectations of 'looking to the man' to be the head of the relationship. We make decisions all together. This sometimes means a decision takes longer to make, or that there are a million texts to answer, but that is fine.
As for the children thing, I think that in any long term relationship people have to agree on whether to have children or not. If one person wants them and the other doesn't, its a set up for a lifetime of resentment and anguish. If you want children and he doesn't, is that something you're willing to compromise?
My girlfriend would like to have children. We already have one child and would like more so we are discussing how to move forward. I would like to have a child with her, and also bear more children myself. Even contemplating this has kept the three of us late into the night discussing things. Having children in a poly relationship seems incredibly daunting! Especially in a FFM triad, where the woman giving birth is not the legal spouse. That said, I totally think it can be done.