His mother vs his daughter.

My daughter is 6 months old, me and my boyfriend had a unplanned pregnancy, and he was still working and going to school so we decided for me to take her and have him stay here on the weekends because he goes to school after work until 10 pm... And he lives with his mother and sister , he pays 600 in rent and his mother just asked for 400 more and he would be paying 1000 dollars to her a month when that money could be going towards our daughter!!! You'd think that she wouldn't wanna take away from her grand baby . So I spoke my mind to him and he broke up with me he chose his mother over his daughter. Please someone explain to me, did I cross the line? Am I in the wrong? When all I want is my baby girl to have things and for us to live a stress free life. I'm heartbroken.