Need help desperately, please help!

I have two friends. For the sake of privacy, I'll use fake names. One is a girl named Naomi and the other is a boy named Jake. Jake likes Naomi. N used to have a small crush on J. I'd helped J confess to N. Due to her small crush, N had said that they'd remain mutual crushes. However, N is a bit of a crush nomad. She's moved on. J hasn't, and he acts like they're dating. For the record, I'm a straight female. He gets jealous of even me when I get really close to N. Lately, J's been saying really creepy things, like really detailed descriptions of his ideal first kiss with N, even though N doesn't even like him in that way anymore. He's asked for fanart of him and N, from ME. J also says pretty often that he wants to kill himself and is very, VERY emotional. N and I told two friends, now the four of us are trying to figure out a way to get N out of this unfavorable situation without upsetting J too much. At this point, we're desperate for a solution that'll help us. Please, if you have a solution, help us!

Here are some solutions we've tried and failed or we can't due to personal circumstances.

1. Online explaining

2. Contact with J's family

3. Drifting N away from J

4. Avoiding leaving N alone with J

5. Straight up asking him in real life