Mema,
Just because something hasn't worked in the past, doesn't mean that it won't in the future...that said, you have had a dump truck full of sadness, stress and pain yourself...So do not be so hard on yourself...the French say "let time heal time" meaning that you cannot rush recovery no matter how much you wish to...
You need to keep active, find a new passion, rediscover some joy in your life...your stress is filling up all or the cracks and empty spaces in your brain, essentially taking over your thoughts...you need something else to fill those cracks...fun is a great healer...I know that at our age it is difficult to find 'fun' or pure joy (granted being a grandparent has its kicks...but they don't come over often enough) but maybe you could find something that really 'floats your boat' a bit...not sure if you are into art, sports, cards, music, museums or dancing but you need to fight the good fight and get out of your house...do things that you have never done, go some place new and take some risks...(fine, in my life, going to the movies is risk enough!)
I get my joy from baking and cooking (and my students that take up way too much of my time) and taking care of others...it keeps my thoughts occupied...no time to feel sorry for myself...
The busier you are the better you will feel...find a new project, plan a crazy trip, take on a 'little sister', foster a kid, visit the sick or take up kick boxing...whatever the activity it needs to put you into contact with others, require you to have fun, laugh and keep busy.
But do not become impatient with yourself...let yourself heal and mourn too...
Hugs
Sharon