When Does The Guilt Stop?

My mom got T2D at the age of 37. She was put on insulin right away. I was 19 at the time and was shown how to give her shots with an orange.

I took her to all her doctor appointments, helped her fix meals, etc. 2 weeks later she died. Went into a diabetic coma. I always wonder if I did something wrong, gave her the wrong amount, or fixed the wrong food.

It's been over 40 years and I still wonder about certain things. Yes, I did get therapy.

Has anyone not let go of guilt after many years? How did you cope?