I had an ex like this. He was the most selfish wanker as well.
This is not to say yours is selfish, and I don't want to minimise his condition because male suicide is often minimised and completely ignored until it's too late. However, genuinely suicidal folks don't explode and tell you they're going to do it and try to leave, they just get on with it quietly. Suicide that's the result of violent self harm behaviour with drugs, alcohol, or cutting for example, is usually accidental from going Just that little bit too far. Pre meditated suicide tends to be a very private and quiet thing.
When my ex was threatening it around me, I pandered to it initially until i got fed up of his dramatics. When i say he was selfish, I wasn't kidding. We hadn't long moved back to up to the area he was from, so we could be closer to his son and family. Turns out he didn't want to move back home because that would be too much like being a responsible dad, and his suicide threats were because he said he was "bored" and wanted to go and get stoned and go fishing with his best mate.
Imagine being that kind of dad, moving away from your son and complaining of being bored when you moved back. He would tell me he never wanted to move back, and it was my fault for making him. Damned right I made him, he needed to be there for his son.
It came to a head when he was moaning to me and his sister about being bored again and how he should just kill himself. He was being completely over dramatic and his sister was panicking, so I called 999 and said I was in the house with someone threatening to kill themselves. They gave me instructions to remove sharp stuff as also to keep myself safe in case he got violent. When the ambulance came, he refused them entry and even though I said they could come in, they told me his refusal meant they couldn't. He started ranting and so they called the police for backup because he was getting more and more wound up.
It wasn't long before he was carted off by three police officers, taken to a cell and evaluated by the district psychiatric team. They deemed him stable and not suicidal, and so he got the lesson of his fucking life that day.
I threw him out soon after. I got fed up of his tantrums and selfishness, and I didn't want to be with anyone who refused to be there for his son as a father. I didn't realise the fullness of that situation until we moved up there, and I talked to his family.
Long story short, next time he explodes please call 999 and tell them he's threatening to kill himself.