I just can’t believe my kids life is like this, he’s right, I’ve failed them
You feel yourself to be trapped by an abusive partner who abuses you in front of your children, and you feel like you have let them down?
Can you not see that you and the children are the victims, and that he is the perpetrator?
What you need to do is demonstrate to your children that, when faced with a poor relationship, you leave. Posting here has been precisely the right thing to do, for your children. It's your first step towards getting out. Having taken this first step, now is the time to start feeling that you're one of the awesome ones; one of the ones that gets their children away from an abuser.
Keep posting. That bit of you that he won't listen to, the bit he surpresses; keep that bit of you talking. That's the bit of you that will get you out of this situation. Use that voice to speak to Womens Aid. They don't say to people 'Yeah, sorry, sounds like you're stuck, love, you'll just have to stay there'. they've seen thousands just like you, and they'll know what to do, what to watch out for, how to prepare, how to speak to the kids... They will support you in the places where you feel there's no way forward.