My partner has threatened to kill me

Hi guys, I'm new here. I'm 24 and female and my partner (male) is 27. Last September we seperated and i stupidly went back to my ex once. Yes I regret it. I made a mistake. I love my partner very much and only see myself with him. He's the one I want to marry and have children with. Things have been very rocky since he found out I went back to my ex. We've stayed together but things have been difficult. Most days he is fine, but some days something just clicks in his head and turns on me. He calls me horrible names, screams and shouts. He says he's thought about stabbing me in the head and killing me. They are just thoughts. Last week whilst out in his car he started acting psychotic. He threw food at me and started speeding down a road saying he was going kill us both. He also said he's thought about driving us off a local bridge. I know what I did was very wrong, technically we wasn't in a relationship. But this is not an excuse. I take full responsibility for my actions, he's even said he's forgiven me but can't forget it. He can't sleep properly and is having nightmares of me leaving him. I've offered help and advised we go to relationship counselling. How can I help him if he can't help himself? It's easier to walk away but I'm prepared to make up for all the hurt I've put him through. I've stayed with him through this violence. But should I stay now that he's threatened my life?

I wouldn't 'abandon' him or you'll compound his problem (he's obviously emotionally overwhelmed by what happened during what was supposed to be just a break (not in a relationship is known as Over), and incapable of reining himself in or expressing it via the usual, more orderly channels). But, yeah, you've obviously hit a giant nerve. Me, I'd tell him that because of how alarmingly out of control he's been behaving, you're too scared to be in the same room as him, but will stay available, within reason, via the phone, until such time as he's had a chance to calm down and regain control over his emotional chaos - which takes time and a lot of reassurance on your part (repetition, repetition...). That way, you get to SEE whether he can calm down or needs intervention by a professional, but from a perfectly safe distance. Then, with any significant improvement, you can up the ante to meeting in a very public, very safe place during the daytime. And so on... Plan?