frustration at work

I have been at my job for 17 years. In the past 2 years there has been a LOT that has happened there. I am the CEO of a veterinary practice. Within this two years, we’ve had 2 doctors pass away (one by suicide, the other by either suicide or accidental overdose). We have also had 2 employees loose their children (one a baby who was sick for about 8 months before she passed) and the other was an adult whose ex stabbed him. Then we have had 2 employees attempt suicide that we were able to intervene on. After the second doctor passed away, I had a mental breakdown and had said to myself I was planning to leave in March. Then in November, things that I have been working for in this business started to come together and I was excited and re-energized and decided not to leave. I am excited and energized much of the time but as soon as something challenging happens (this past week was the second employee that we were able to intervene and get hospitalized) I get overwhelmed and immediately want to leave. I know that leaving is actually not the right decision for me at this point because I am the primary bread winner and we need the income. I have done the model on this many times but obviously am not working my thoughts because I keep ending up in the same place.