I never thought we'd be all you needed. I never thought you didn't need things elsewhere. I was not upset that you found these things in him. For the most part I was really happy and I tried to be quiet about how it hurt to know that I had wanted to have many of those things with you, had tried and failed. It wasn't your fault you didn't feel the same and you didn't owe it to me to do that.
I was upset that you weren't honest about where the relationship was when talking us. I was upset that the two of you had all these plans that moved him into our relationship and home without is having met him. I was upset that he was always present but you wouldn't try things to let is interact with him early on, like speakphone or sharing the text conversation. I was upset that you disappeared into him when i needed help, that I was more alone than I needed to be during my pregnancy and maternity leave because you refused to come back. I was upset that you told me things i didn't realize you weren't telling our partner, only to have him get mad at me. i am upset that i get punished for having any response except the exact one you want to everything but everyone also gets to get angry at me for having emotions and that is also considered ok. I am upset that "i dont particularly like him or want to hang out with him" has translated into "everything must be a secret", since I had tried to listen to you and be supportive of things and tried to recognize and verbalize and correct them when it was me having issues, especially since things being secret only add to my anxiety and detract from the reasons I had an open relationship to begin with.
I am disappointed for everyone's sake that because of personalities and how everything happened we do not particularly like each other in a way that would foster adding him to the family because I do see what he gives to you and I do want you to have that. And if it didn't mean leaving our child, soon to be children, I'd even leave, just see our partner when we had free time, so you could do that. Gods know he could keep your house as well as I. (Except for maybe the laundry, but you could teach him to do that.) I just can't find a way to keep our shared partner's family together without being here.