I’m going to have to miss out some context here so as to not be too outing, but I’ll try my best to explain the situation.
So, I’m a middle child with an older half-brother and a younger half-sister who is only 13 with additional needs. Our DM cut my brother’s dad out of his life, making him believe his dad walked out. She tried the same with my dad, but he fought for custody so got to still see me.
DM met my sister’s dad when I was young, and my brother and I saw him as a real father figure. They had my sister, but years later, broke up. DM then blocked him and my sister’s grandparents from seeing her. My sister now sees DM’s new partner as her dad and thinks her biological dad doesn’t care about her.
When I turned 18, I moved in with my grandparents, realizing the truth about DM. Now, pregnant with my first child, I’ve reconciled with DM because I need her support during my pregnancy and want my son to be able to have a relationship with his grandma.
Today, I got a message from my ex-stepdad, asking me to pass a message to my sister, saying he loves us and wants to fix his relationship with her. He has no way to contact her and doubts DM will help. If I pass the message on, DM will find out, and I don’t want to risk our fragile relationship so close to my baby being born. But I feel guilty keeping this from my sister, she deserves to have a relationship with her dad, and he equally deserves to have access to his daughter. I haven’t responded to him yet because I’m torn about what to do. AIBU?
(Also, I wrote this in my notes and copy and pasted here, unsure why it's a different font - please ignore that!)