You mentioned you'd been together since you were children, so neither ever really had the chance to grow up and mature as independent adults, to live the single life. That's unfortunate - but can't be changed.
Both of you came from difficult, unhappy backgrounds. You've experienced the consequences of two lost children finding each other, clinging together.
Now something's happened - as in, another responsibility and tie-down in the form of a second child he claimed to want - and he's cracked.
So your goal, your hard road, must be to ensure your own children have as stable, calm, happy and supported lives as you can possibly give them, to break this pattern.
If there is no abuse, facilitating contact with their dad is wise, and will head off any accusations of parental alienation from him or his family, and 'you never let me see my dad' accusations when they're older.
I hope you've seen the solicitor and have a solid grasp of your rights and your property.
I'd advise get back to work as soon as you can as and when it fits your childcare - income, savings, pension and self esteem will matter.