How do I move past losing my Dad to dementia and having to put him in a Nursing

My Dad passed away 2 years ago and I am still struggling with the guilt of putting him in a nursing home. Logically I know that I couldn't give him round the clock care at home but I still torture myself with the what-ifs. A lot of our family and friends turned their backs on us when his dementia started due to being uncomfortable with the changes in him and then some of them judged us when we had to put him into care because he had become aggressive, irrational and unpredictable which culminated in my mum having a heart attack from the grief & stress. I can't let go of the sense of helplessness and abandonment as well as grief. How do you move past it?