What steps can I take to end my relationship with my partner who is experiencing suicidal thoughts?

I'm bracing myself for a wave of criticism for sharing this. I've been with my partner for four years, and while we’re both in our early 30s and he lives in my house, we’ve always faced challenges. The good moments are truly special, but in hindsight, I realize there have been more difficult times. For a year, we were quite happy, enjoying nights filled with smoking together, which seemed to mask our problems. Last year, he lost his job, something he was relieved about since he disliked it. He decided to take a break before searching for something new. After several months of fruitless interviews, he felt he had no choice but to return to the same company in a different position. Since going back, he has been miserable and has already faced another layoff. A couple of years ago, I supported him emotionally to the point where I felt overwhelmed. Now, he’s struggling and is feeling suicidal, while I’m trying to guard my own mental health. I worry that my efforts to protect myself are making me seem unsympathetic, and I'm terrified of slipping into that dark place I once faced. I’m also exhausted; we’ve never taken a vacation or enjoyed any of the activities most couples do, despite my attempts to create those experiences. I’m emotionally drained, but leaving him weighs heavily on my mind because I fear for his well-being. Recently, he's been more confrontational, and I just want to escape this situation.