I’m sorry for your situation.

Having gone myself as a 5 year old sibling through something like this I wish to stress this:

Don’t let your other children become chronically mentally ill, send them to the psychotherapist and counselor and do that for years. You can’t imagine the amount of suffering they will have untreated. This is not something that you can just outlive and your children are dependent on you supporting them by giving them support from somebody who actually can support them. The scar of this trauma will run many many years, make them extremely vulnerable and can render them with a full blown disability.

You can prevent this. Don’t let other people who have no idea shame you for seeking help for this.