This is a really difficult situation. I can completely understand where you're coming from when you didn't want to judge him about his addiction and his domestic violence case. You have obviously developed a strong connection with this person and it's amazing that you were able to see beyond his struggles.
I think at the same time, your intuition is very important. It's important to look out for the warning signs of abuse and relapse when deciding to be with someone with this background. Everyone can say that they've changed, but change is demonstrated through actions.
Your partner has been verbally abusive to you and drinking again, even when you have supported him financially and emotionally. Abusers seek to control and have power over you to get what they want. I understand that you have empathy for your partner and know that he's struggling, but this can never excuse abuse. You can still love your partner but have boundaries for yourself.
I can't tell you what to do by any means. But I strongly suggest that you put yours and your kids wellbeing and safety over his. If he's the right person for you, he will show you that he's changed and come back. It may be that in his own life he isn't fit to be in a relationship right now, and he has a lot of work to do to get back on track.
You can still love and care for him while keeping your distance. Do not ever let him get away with this behaviour, especially considering what happened with his last partner. It takes a lot of recovery and desire to change for an abuser to resolve their issues, and it's his responsibility to take those steps.
If he is right for you, he will show you.
I really hope that the love you have for each other will lead to a healthy relationship one day for the both of you. From an outsider looking in, this does seem like a dangerous situation and I strongly encourage you to look after yourself here and keep your distance. The person that you once had a connection with I'm sure is still there somewhere. It's his job to prove that to you, and it's important that you don't sacrifice more than he will to get back to where you both were.