I'm new here but finished reading through your blog. I've been confused about the dynamics of the beginning of everyone's involvement so I found your introduction. It is amazing to me that Lamian started seeing Seven when she was 13 and he was 15. After finding this knowledge, I have to say that both of them are still very immature in dealing with their feelings and the bottom line for both of them appears they are just very much co-dependent on each other.
I don't know if a couple who started seeing each other in their teens and never dated another until their early 20's will ever be able to have healthy relationships without being on their own. To me, for you, means any type of relationship with Seven will not be healthy until he really finds himself and can be on his own.
I wish you luck on this journey and honestly, moving out with your husband will be best for you. You're needs are ignored, you are treated like you are the one immature on this adventure (both Lamian and Seven have been projecting onto you their personal immaturity issues) and it's not healthy for you to stay with them. Letting go of love is a hard task to accomplish but for your sanity, you should ask yourself if it's all really worth it? Trust me, you'll have bad days and good days and there is so much more to your life than having these two in it.
The world is your oyster, so to speak. Why not get more in touch with your self, your husband (who appears to be an introvert) and focus on you two for now. I didn't come to poly until recently and I am 41. Have I missed out on much? I don't think so and I still have many more years left to share my love and myself with others.