Hi goataholic,
Welcome and hello

I wanted to join
Huat in welcoming you to the site. I understand the punishing guilt you talk about. My son was always an exceptionally sensitive child and frankly, the emotional intensity was something I didn't have experience with.
The skills needed to support our kids are not intuitive, and even without the intense grief you must have experienced, it is possible your son would need more than you could have provided. I think boys who are emotionally sensitive have it even harder because empathic abilities can be actively discouraged, not just overlooked. This is so invalidating for children who need a lot of validation.
Is your son in touch with you? Does he have a relationship with his siblings?
For me, a day doesn't go by that I don't experience some guilt. I allow myself to sip from that fountain for a short period, and then I move forward and build strength so I can forgive and feel compassion. There are also skills you can learn that may help your son with his emotional dysregulation, if he reaches out to you when he is stable, and even when he is at his worst.
Keep posting. It really does help

LnL