I feel so upset 😭💔

I'm currently 26 weeks pregnant with my bfs twins. Recently he sent me messages from his other sons mom saying something along the line of how he needed to sign his son away to be there for me and out 2 children. My reasoning for being upset is it's not the first time she's asked and she's a very munipulative person and I feel it's not okay for her to be using MY children to minipulate him to sign away his son. I'm also aware that their conversations based on a court agreement are to only be about THEIR son. I have asked him several times to please refrain and to politely ask her to refrain from bringing me up in their conversations. I just recently found out that he has not defended me or my reasoning in being upset about her using my kids as pawns in her sick game (he has been in court the last 5 years battling for time with his son due to her keeping him away). I'm hurt. I feel like he should be defending the family he's trying to build but he just bows down to this woman after everything she has out him through. I got called immature for reaching out to her and asking her to stop using me and my kids in their conversations.. maybe I am?! I feel as though I have a valid reason for feeling this way. I'm never okay with kids being used as pawns for power against parents and now she's bringing my unborn children into her game.. and he can't even defend us. These hormones really suck right now.. and I'm not sure if I may be over reacting or if my reasoning is sound 😭?!