I am very sorry to hear about your severe and persistent depression
symptoms, and I am also very concerned, as you are, about the persistent suicidal ideation, which is extremely dangerous.
In the short term, the most important thing is to set up a safety contract with your psychiatrist
or with another health care provider that you trust to help prevent another suicide attempt. Also, if you are feeling acutely suicidal, it is extremely important to seek immediate emergency medical help, such as by going to the emergency room of your local hospital.
In the medium to long term, it sounds really critical that you get help from a psychiatric specialist who is skilled in dealing with the more complex cases of depression. You will need to talk with your current psychiatrist or primary care doctor
to get help with this referral process, because who you need to go see will depend in part on what part of the country you are in and what the psychiatric referral system looks like there.
Ketamine, unfortunately, is used only investigationally in the treatment of depression and is not approved for this indication. There are a few small trials looking at this but, once again, you would need help from your current psychiatrist to determine whether enrolling in one of these trials is an option in your area of the country.