First, your baby is going to be fine. If you divorce, he will grow up and two households will just be his reality. He will not have to grieve the change like an older child would. By the time his is in the first grade, around half of his peers will be in the same situation.
I separated when my DS was 6 mos and had many of the same concerns. I also breastfed, which meant pumping during visitation, sending milk, etc. It can be done.
Ask for everything you want in your papers. It is the starting point of negotiation. If it goes to court, the judge will figure it out, and they tend to be biased in favor of the mother. There is usually a timeframe in which you have to serve the papers, so check with your attorney on what your next steps are.
Being away from baby is a horrid thought. It just is. However, what I have found is that I am a better mom when I have some time to myself. I need it. Usually, there are tasks that need to be accomplished, that are simply much, much easier without baby in tow. Additionally, you will need social time and eventually you may want to date. For baby, it gives a break from the normal routine and caregiver and allows for an attachment to form with the other parent.
Just take one step at a time and soon the path will seem more clear and manageable. Hugs to you and your little one.