I would never be the reason her mum and dad aren't together
You wouldn't be, he would be. He is not giving either of you the time or attention that you deserve. That's not even taking into account his apparent need ot get his kicks elsewhere. These
I get no special attention, compliments, any of his time..he gets up, goes to work, comes home waits for dinner and goes to bed on his phone until he falls asleep. Barely pays DD attention and I get half of that again!
are not the actions of a decent man. I would even say he treats you as a housekeeper rather than a sister. Do you really want to bring your DD up to believe that she deserves nothing better than a man whose attention she has to beg for? Do you want her to think it's ok that daddy treats mummy like shit? That this is normal?
The best thing you can do for your child is model a healthy relationship. Children learn so much from their parents relatiopnships. If your relationship is NOT healthy it can do far more damage if you stay in it than if you get out and model being a decent parent on your own and then in future a relationship where you are treated right. Don't teach your daughter to settle for an asshole because she was unlucky enough to not see his true colours until after she had kids.
My dad walked out on my mum when I was 7. I don't remember him being at home but I do remember my mum being absolutely fucking awesome after he left. She taught me how to run a house, change a tire, change a lightbulb, wire a plug, plan a budget and allsorts of other things. She taught me that I can do anything I want for myself. She also taught me that it's better to be single than unhappy.
These are lessons I've learnt and I believe that because of them I'm married and very happy. I didn't settle for anyone who treated me with disrespect. I had an abusive twat ex but I kicked him to the kerb when I woke up to his behaviour and realised that I deserved better. You deserve better also.