Can you ask him for some more support? I see many parallels between our situations (partner(s) wrapped up.in NRE, feeling neglected, jealous, pregnant, one bio kid two step). My coparent's NRE partner is in my house and is my girlfriend also, so I recognize the dynamic is a different beast but I know if my partner, G were spending all of his non work time with his new and exciting NRE partner and leaving me in the dust, I would be out of my mind.
You say you are working on your issues on your own and that's great, but I think it is reasonable.to ask, if not demand, that he offer some help and support. Just because they are difficult to deal with, or you yourself are difficult to deal with right now, doesn't make.it ok to just abandon you with your baggage because there is an easier option over there. Please correct me if I am making the wrong assumptions.
I tried to take on all my jealousy issues by myself when there were things that my partners could do to support and help me. I had to have a crazy crisis happen to finally feel like I had the right to ask for the support I needed. You don't need a crisis, just ask for, or demand a little help. The jealousy and insecurity is so much easier for me to deal with now, maybe that option can work for you as well. I don't know what your particular issues and needs are, but you shouldn't have to face them on your own.