From the child's perspective, having been in that situation twice and seeing my siblings go through it too, its ****ty and it sucks. Its a horrible feeling.
My biological father has only ever contacted me on my birthdays when he isnt in jail. Twice. Christmas, yeh forget it.
My stepfather was abusive and would also play the guilt trip with me. Id get a happy birthday but never anything more. When he and my mum split you could see despite raising me for 11 years he started to favour his own children. We went our seperate ways when i was 15 after a horrific holiday that ended in me with a broken wrist and heavily bruised arm. Havent recieved anything since (mostly cause he feels he is the victim).
He now terrorises my brother and sister, emotionally. Constant guilt trips. Forgot my brother's 21st this year and then teared strips off my bro for choosing to spend mothers day with mum rather then seeing him for his bday.
Anyway point is from a childs perspective all we want is that father/child relationship and will hold on to anything for it. Even while being hurt.
It takes alot to see it happen, i hate seeing what my siblings go through, i can imagine it would be harder being your child.