Christin,
You are right to think your husband is trying to manipulate you into coming back and making it all better for HIM.
He is.
The question is, are you going to sacrifice your children on that altar?
I was raised by two alcoholic/addicted parents and it took me several decades to feel good about myself again. I had drinking problems, got involved with addicted personalities, and generally went through hell. If you continue to expose your kids to him, your kids may live the same kind of agonizing, self-doubting life that I did.
I urge you to get as much local support as you can. A good lawyer or legal aid to counsel you about a fair separation that allows the kids to be with him when he's proven himself sober. A good Al-Anon group that will help you cope and let you cry and vent. A good relationship with your sister, along with a way to keep communications open -- maybe touch in with her once a week with "How are we doing? Is there anything we can be doing better?" or similar...you'd be amazed at how helpful this is.
Cultivate the friends you let slide because of your husband. Spend some time thinking about what you want out of your remaining 60-70 years (I'm thinking it may NOT have much to do with playing wet nurse to an unrepentant alcoholic who belittles and hits you and doesn't even pay his own way in life) What's your dream? What are your children's dreams?
A good place for him to start is to get sober for a year. Then you can revisit your relationship. With him, not even willing to stop, walking back into that relationship would be hell on earth for you and your kids.
Limit contact with him. There is a monster behind that mask -- we've all been through it. He knows all of your soft spots and he is working hard to make you do what HE wants you to do.
Take care of you & the babies, Christin.