AITA for taking my daughter's side?

I have a daughter(14F) with my ex. My ex in total has 4 kids, 1 with me and 3 with her current husband(9M, 7F, 4F).

She had to downgrade her home because of some financial issues and now they live in a 3 bedroom home.

Yesterday my ex called me angrily and asked me to talk some sense into my daughter. Apparently my daughter and ex had a huge fight when my daughter found out she is supposed to share a bedroom with her half brother, my daughter told her mom that she wants a room for herself or she will stop going to her home.

I told my ex while I understand that she has financial issues but she needs to understand that my daughter shouldn't have to share a bedroom with her brother if she doesn't want to do so. I said that I think my daughter is right and asked if I should pick her up since it seems like she is not willing to give her a bedroom for herself. She called me an asshole and ended the call