I agree with the advice given above. I'll add:
Get a job. You'll need income no matter what you do going forward whether it's moving in with your mom or getting your own place. You can get free job search help from your local unemployment agency. Find one here:
www.dol.gov/dol/location.htm. Maybe even work at a daycare or school where you can take your child. Some need administrative work done. Set up a free Google voice account for potential employers to leave messages, etc. You can set it up so that the voicemail is kept on Google and not forwarded to your phone.
Speak with a family law attorney or counselor. Local bar associations usually offer "lawyer referral services" where they will match you with a local attorney specialized in your field of need for a $50 consultation fee. You could also go down to family court and speak to court administrators to see what you would need to file for primary custody and for child support. It doesn't happen often but some men have fought for custody and won as they were better able to provide their kids than the mothers. It sounds like he would fight for it. Keep a record/copy of his social security number, employer info, bank account numbers, insurance policies, retirement accounts, etc. Whatever you can get information about that is worth something to him in value.
Talk with someone you trust - not him! I would not tell him anything about your plans. NOTHING! Don't even bring documents home (job stuff, court docs, etc.). See if you can keep documents in a folder at a friend's home or at your mom's place. Don't use a family computer to check email or do research. He may get suspicious and check your search history or be able to log into your account. Use computers at the library, your mom's place, etc. Even local state unemployment agencies have computers for job seekers to use daily for free. As a matter of fact, change all your passwords now on your email account, phone, etc.
Look into domestic violence programs. I was told that Maryland has some program where they will put up a woman and her kids in a local hotel before moving her into an apartment where they pay for her rent for a year until she can get on her feet. My friend was going to rent out her condo to someone in that program. Not sure as to the name of it but your state/city may have something similar. Oh and domestic violence is not about some guy beating you to a bloody pulp. If he is restraining you, belittling you, etc. then you are enduring emotional and physical abuse IMO.
Seek out "free" childcare. Maybe mom can help watch your child once a week for three hours while you go to the library, apply for jobs, etc. A good friend may do so too. Check with local churches. Some have Awana programs (
http://awana.org) that kids participate in for a couple of hours each week. You could use that time to redo your resume, read a book, get mental clarity, etc. while getting a break from childcare and from him.
Workout. Find time to get in some physical activity every week. You could walk around the mall, parks, tracks, etc. several times. Walk to the library, grocery store, etc. When you look good, you feel good. Being in a space where you feel trapped doesn't feel good. You'll need to feel good about yourself to take an empowering step in your life.
Good luck sis!