With leaving, yes you are staying out of fear and to minimise the risk of extreme harm to you and your children. That's part of how abuse and abusers work.
He may not actually be allowed unsupervised contact if you know what to do and who to talk to. He is abusing your children, after all. I do honestly wish my mum had left and he only saw me at weekends, though. I would then be safe 90% of the time rather than never knowing when something might happen, I'd know it was abusive (maybe have got counselling) and been able to report anything that happened or stop contact myself as I got older. I also at least would not have to watch him mistreat my mum, that felt worse than what he did directly to me as I loved her so much.
You need the support of a specialist agency like Women's Aid. They will be able to guide and advise you about issues such as child custody and how to leave safely, to reduce the risk of him blowing up, or refer you to solicitors experienced with such things.
Leaving is the most dangerous time and my dad did take it out on my brother and I, to get at mum. She didn't know she was being abused though until it got to that stage or what to do in order to limit the risks. While it was traumatic I don't regret what happened in that I have nothing to do with him now. Life is so much better some days it doesn't feel like reality. -- When we got in touch with Women's Aid we finally got the tools and understanding we needed.
If you do stay, if only while you wait for the children to get a bit older or to arrange leaving in the safest, smoothest way, there are things you can do to help protect yourself and the children.
It would have made such a difference to me if my mum acknowledged things were shit and when he was behaving badly, and given me comfort after he was abusive towards her or us. Women's Aid might also be able to help you with a safety plan, as he is likely to get worse over time. These type of men don't really mesh well with teenagers for example, who are harder to control.
And counselling, God do I wish I'd had some as a child or young person. Instead I have had to have it as an adult and it's much harder to recover or changed embedded ways of thinking or feeling.
As to suicide...genuinely suicidal people don't use suicide as a threat. That again is abuse. My dad did that too and used to tell me how he was going to kill himself because of what an awful daughter I was. I had mum running off after him when he threatened it, and then I had his emotional blackmail plus worrying about what he was doing to her. -- Don't engage with it. Honestly, it'd be easiest if he did kill himself. Let the bastard crack on. I eventually used to tell my dad to get on with it and that he wouldn't be missed due to his actions. Because why would he be? I stopped loving him when I realised he didn't love us and was hurting up on purpose to get his way or to feel better about himself. Mum still felt responsible for him and to me as the child it hurt she put him before her children and didn't see she was exposing us to harm by letting him manipulate her life that.
My brother summed it up best anyway 'he loves himself too much to kill himself.' and it's the only person he does love.
And why will he have no one? Maybe because no one else would put up with the monster he has grown into? He doesn't feel sorry for you or the kids, so don't waste emotional energy on him you should save for your innocent children, who do have a chance right now, if you give it to them. It's too late for him, but not for them.