When it got to a point that I was making careful plans for how to effectively remove all traces of my existence before walking into the sea or something, I realized that it was probably not a good thing that I was fixating on this "fantasy" and how attractive it was becoming, so I went to a nice little family mental health clinic in walking distance.
I was diagnosed with depression, PTSD and general anxiety disorder. A few years and a few rounds of therapy and medication later and I'm... still struggling. But at least I'm not planning my exit. There's a lot to live for, but you can't see it when your brain starts running away with your mental narratives. Don't ruminate, don't fantasize. Get some help and do something new with your lives.
I'm in a similar situation. I recognize the planning of my exit. I used to do that in the past.
Or well. Maybe it's not all in my past yet. But I'm doing my best.
It's hard to ask for help, but it's worth it. Life's a mess, but it's worth the struggle to get through the bad days. The right refime medication and (NON-CBT for me) therapy were farging hard to find and keep attending/following.
Good ideas, all around. I'm glad you didn't walk into the sea. I have walked through that dark place myself and it led me to get a therapist who knew exactly what that was like. I learned how to help myself. It's been ten years since then.