Poor you op, peeps here are giving you wonderful advise and of course you can read around the how to leave your abuser on many of the threads in relationships forum.
Take a deep breath and go at your own pace,
Get real life support,
Get on record what is going on for you (and dc), your gp (ask for counselling, this will help support you), school, womans aid, police (non emergency, ask them for guidance and log the historical abuse of when he called them when you went to your mums). Speak to cab, benefits, solicitor (get you free half an hour, go to as many as you can in your area, you should get a firm idea of what and how things can be done).
All of the above is important as it leaves a paper trail, you may need this in the future.
Go through maintenance for the money that is rightfully for you to look after the dc. Make sure that you have copies of finance, bank accounts etc, passports, birth certs, marriage cert. keep this documentation safe, maybe a trusted family member or friend (keep copies for yourself).
Do not engage with him other than email (can be used as a legal document), text if you can screen shot and email. If needed for your sanity you could block his phone number.
You need to plan your exit and doing some of the above will give you the help and support you may need, it also gives you a framework in which to operate in. Arm yourself with knowledge and people to help you, one step at a time.
Be ready for the emotional side and in this sort of situation be ready for him ramping up the abuse, when he does, turn to your framework and log everything.
Good luck and keep posting.