Ah, BP, glad you checked back in. Sorry it's still uncomfortable for you in your "triad becoming a V."
Now is the time for you to insist on some focused attention from your husband. Even tho he and gf are in NRE, it won't kill them to take a week off, it really won't. If I were you, I'd request he take a week off from seeing her altogether, and spend focused time with you, and your kid.
I'm in NRE with one of my lovers, and I only see him once a week. I don't live with my primary (miss pixi), we each have our own places. So, I see the Ginger midweek at my place, for an overnight, and see miss pixi for several days each week, over a long weekend.
Your h and his gf seem to have a bit of understanding about NRE, but since they don't want to be apart, they've been insisting the NRE is handled by you being around them and immersed in their passion. Obviously this isn't working.
Unless she's a cowgirl, your gf should respect your primary relationship and allow you and your h some space. He also should come home to you, spend time with you alone and keep your pair bond healthy and intact, and fun! It's his duty and also should be his pleasure, to talk to YOU, hug YOU, snuggle YOU and date YOU.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
Mags (poly, F, 61) loving miss pixi (poly, F, 39) since January 2009, living together since 2013
Punk, 42, ex bf, manchild. I've been Punk'd!
"Master," (mono, 34), miss pixi's Dom for 2 years