Custody please help!!!

So I live in Michigan and have decided to leave my verbally abusive SO who we have a 5 month old with. We are not married but I need to file for custody...is this a legal matter that would require a lawyer or Just paperwork? I’m not sure he would want custody...he always claims no when we fight but I have no clue when it would come down to it how he would proceed. Thanks! (I’m literally packing as much as I can not and basically fleeing as I write this)

Also he asked me to be a stay at home mom when I got pregnant so after working my dream job for 11 years I quit to be at home. We were supposed to get married so I’d have insurance but he has kept postponing that. So now I have no job to top things off.