Hi Inv21917,
Sorry to hear you are at this very difficult moment in life and are having to consider this very difficult decision.
How long have you been married? And how old are the kids?
It is hard to say if you should try to save the marriage, that is such a personal choice and requires interest on his part as well, but since you do have kids together you would potentially benefit by completely adjusting your communication style with the father of your kids since you will be interacting with him to one degree or another going forward.
There are a lot of lessons to the right of the board here.

Have you had a chance to begin with any of them and consider the implications for your own relationship?
You know him well, do you think deep down he may want things to work but, like you, is just very frustrated, hopeless and not sure what more he can do? Relationships driven to that point can be pulled back from the brink if changes are made. Are you willing to make changes to cope with his mental health issues? It will likely be you who has to lead on this.
At this time is the divorce in process? How long until it would be considered final if you two don’t stop the process?
wishing you the best, pearl.