Mantra - I hesitate about posting this, I hope it is helpful. I write it in response to the idea that you are in any way to blame for what happened, which of course is not true.
A friend of mine who had serious MH problems once described to me what feeling suicidal is like with this amazing metaphor. He said that it's like your emotions are a vase for collecting and carrying rainwater. Normally, it rains for a bit, but the rain runs into the vase. We might occasionally have a moment where the weather gets rough and we slop over a bit, but we basically feel the vase is solid and will carry the weight of the water.
He said that when MH problems start, it's like we are in a monsoon. And we start to have fears that the vase is cracked, that it can't cope with the deluge of water that is coming. So we try to struggle on and ignore it, but soon we start to see leaks start streaming out of the pot from all directions. There's no capacity to deal with or to hold the water that keeps on a-coming, relentlessly, out of the sky. Hairline cracks widen under the strain into fissures, and there is water, water all around - the vase itself stops being in any way a container and starts floating on an uncontrollable tide. All of the voices that tell us that we should speak to someone else, and ask them to take a bit of the water for us, to anchor us down are muted - we don't want to be a burden to them, we don't feel it's fair to ask someone who is also trying to cope in their own weather for assistance. In the end, the stress and strains of it all are so great, and the effort feels so futile, that we come to a point where we genuinely believe that the only way out is to take a hammer and smash the vase to smithereens. Only then will it stop raining.
Sadly, my friend ended up taking his own life one day after years of battling with these feelings. He was a lovely, sensitive soul who was creative to the core of his being - he wrote amazing poetry and ran his own poetry magazine. And yet he couldn't himself see how much he enriched the world of everyone around him. I hadn't heard from him for some time before he did it, and then all of a sudden he popped up on Facebook, messaging me. He didn't say anything was wrong - he sounded cheerful. But he must have been looking for someone to talk to, and I clearly didn't respond to him well enough for him to trust me. I just thought it was lovely he had gotten in touch and did my usual airheaded thing of chatting away nineteen to the dozen. I wish he had talked to me. I wish I had put two and two together and wondered why he'd suddenly contacted me. And then he was dead a couple of days later. 