I think you are doing good self care. Stating that you have a good history of never wishing to end your life helps you to have a base to stand upon. Yes, I do think that added stress can add to the darker thinking... and perhaps your inconsistent psychotherapy has allowed for the depression to deepen as well?
Oh my you have had such a big change in your life! While I agree that you need to be concerned, and speaking to someone on a regular basis about the added problems and feelings you are encountering, I think along with that you can trust yourself to keep putting one foot in front of the other inspite of not being able to see "the end of the problems" yet.
Do each day by itself at a time. When any of look beyond our capabilities..into the future, we can become so discouraged! None of us can predict the future. By reading just here at PC we can see where lives totally change around in the course of one or a few days...often unexpectedly and for the better!
Using your children as a reason to keep going is a good one! They trust you for that, and I feel you can follow through. I also think that you have spoken the situation well... you don't want life to end, you want your life AS YOU NOW KNOW IT to end...to change for the better. Keep on keeping on, you can do this! You aren't alone... many of us have walked the same steps feeling the same way