Divorcing my husband...

I have been with my spouse for 15 years and married almost 7. Our relationship has had it's fair share of ups and downs but things definitely changed once I became pregnant. My spouse became distant, unsupportive and argumentative. I thought it would change once our son arrived but it's the same, if not worse. No matter how hard I try to walk on eggshells, we continue to butt heads...arguing often. Our son is now 4 months old and I've finally had enough. I realize that he's never going to grow into the man, husband or father that I had hoped. I blame myself for not realizing this sooner or going for divorce out of fear of what people might think (I dont know anyone that's divorced) and now there's a child involved.

I've reached out to consult a divorce attorney to weigh my options. I'm waiting to hear back from them.

How would I go about getting custody of our son? Do I even have a chance? We currently live together but I have been looking to move into a bigger place (we have a 1 bedroom apartment in NYC and our son will need his own room). I know that my spouse cannot afford to live on his own (I make double his income) and will be forced to move back home with his mom or crash on a friend's couch. He's not physically, emotionally or financially supportive of our son. I am the primary caretaker and do EVERYTHING. I'm basically a single mom that's married as crazy as that sounds.

Has anyone ever been in my position? I literally don't know which way is up right now. All I know is this is what's best for my son and I and I wish I was already done with the process instead of not knowing where to start

Any help is appreciated