How does a mom let go of her kids, why can't they forgive her?

At age 56 I continue to deal with severe depression. I have had 2 surgeries and 2 additional hospital procedures this year alone. My meds get changed and I don't react well; causing upset and anger in my family. How can I explain that some losses (a mom dying @ my age 3) repeated bad relationship choices, etc., plus more disappointment for my children when I voiced one thought of giving up and ending my life. I wished I had not said it as soon as it came out of my mouth, I have explained how meds changing have caused so many problems, but my children still want to sit down and clear the air about all the things I have done to them and how disappointed they are in me. My meds are still being adjusted and it may take more than a few months to do that. How can I explain that? I believe it has cost me more than their not wanting to visit me, but having contact with grandchildren seems to be vanishing. I believe my son will not ever visit me-he told me that over a year ago-yet hearing of his family visiting all of their family except myself and my husbands does hurt. Do I let go and just pray that someday it changes, or do I begin to let go painfully, my loved ones. I may have caused this severing, but is there a point where children refuse to accept apologies and just pick up and go on with the emptieness? When I first moved 2 1/2 hrs from their home I understood no visiting, yet my children will visit their aunt and father who also live between 2-3 1/2 hrs from their home.