Does Childs age impact custody %?

I need to leave my husband. He clearly dislikes me, disrespectful, mean, doesn’t help at all etc.

We have a 5 month old baby. He said he would want 50% custody. Does the fact she’s 5 months old (not breastfed) impact the decision of what percentage of time he has custody of her?

Secondly, I am concerned for her wellbeing to be with him for prolonged periods of time. He can’t handle a few minutes with her before handing her back to me. The longest he’s taken care of her is 1-2 hours. If she cries he ignores her because he thinks we spoil her if we attend to her crying. He either plays on his phone and completely ignores her, or just lets her cry. Days at a time, even 24 hrs of that is horrible for a baby and I’m concerned. Is there anything I should be doing now to build my case and demonstrate his behaviour?