I need support and opinions

My daughter (7mos) has not seen her dad since she was 2 months old (June/July). He told me if she needed anything to contact child support and get it increased. (I didn’t put him on cs my state did). I’ve constantly begged him to come see her and things like that up until November. I stopped asking for help and asking for him to come visit. I posted pictures of my daughter and my so since my so spends majority of his time with her if he is not working. I just received a letter in the mail stating he is fighting me for full custody. All because my so stepped up. I’m hurt by all of this. My child’s father has not bought her anything at all. No visits or calls on holidays. I’ve tried to FaceTime him just so she can see him and he didn’t answer but now he is fighting for custody. I need advice, support, and most importantly prayers!