VERY new to poly - feeling "wrong"
I am brand new to a poly emotional relationship and I have several questions. For background, I have been in a committed relationship with a man for over three years now. I am bisexual and so among these three years we have done a few threesomes and I have experimented with women. I've also tried giving him some leeway and allowing poly sex among a small group of female friends. My SO is very uncomfortable with other men being with me and he is not bisexual so the idea of dating another male has not come up and I'm really not interested in it.
About a month ago, we met a woman that we were both instantly attracted to. After a party she and I were sexually active and later on, we all engaged in a threesome, which was enjoyed by all. We have no problems whatsoever sexually. She is also a sub and my SO is a dom, although he and I do not practice BDSM b/c I am uninterested in it.
Originally, I only felt comfortable with threesomes and them being intimate only within the areas of their sub/dom relationship. Then, the NRE (as I've seen it referred to) kicked in, and without realizing it, within the span of three weeks, she's living with us.
We've talked about doing date nights, which I enjoy, but I've found myself less and less emotionally involved with her. She does not want to be secondary and I am uncomfortable with that. Something feels "wrong" about her being here all the time and I feel jealous and stressed out most of the time. I feel lost in my own relationship, as if I no longer have my place. I do not know if I can ever be comfortable functioning as a "triple" instead of having my own place and my own time with my SO.
Neither of them seem to have a problem but when I mention taking a step back and taking it slower neither of them seems to like that idea. She feels rejected and he feels like I am not allowing her in to my heart, which may be true, but it's because I feel somewhat usurped.
I don't know what to do. I am ok with breaking up with her as a couple but I do not want to anger my SO or hurt her. I would like to continue to be friends or even try poly but I'm not sure if I will ever be comfortable with the situation as it stands. I enjoy alone time with my SO more than our three time and I want to be the primary, which she is not comfortable with.
Advice? Experiences? I really appreciate that there is a support group so wide out here.