Therapy will not work here because he is abusive and there is really nothing to work on.
What did you learn about relationships when you were growing up?.
What do you want to teach your children about relationships and what are they learning here?.
Why do you want to work on this when he’s not bothered with you anyway as well as abusive?. It’s over or it should be and was over a long time ago. He’s robbed you of many things and the only good to have come out of this is your three children(I guess they have his surname rather than yours).
Your boundaries here in relationships are really poor and he’s taken full advantage of your youth and lack of life experience.
Do not stay in such a poor, let alone abusive, relationship because of the children. Abuse is not about communication or a perceived lack of, it’s about power and control and currently he has absolute here. He’s done you up like a kipper. He chose not to name you on his mortgage deliberately and lied to you about the reasons for not adding you either.
Feel the fear and start planning your exit now and with due care. You met this man when you were a teenager so you likely have no real idea of who you actually are because he’s stifled you emotionally and financially.
What sort of job will your training led to?. Can you start finding paid work now or will he likely sabotage any attempt for you to enter the workplace?. I would in any case start looking for paid work and have your wages paid into an account he cannot access.
I would also suggest you contact Womens Aid and get their advice too.