You are going through the stages of grieving that so many of us have also gone and going through.
You lived your life with some cost and reflection will show less regret than others. We all have some types of regret on some things but on this matter, you did your what you needed to do and are ok with that.
That is good progress. Like yourself, I have had to deal with a difficult parent who took things to his grave to the hurt of his family. That said, I did my best and while in my case there is more work to do, I'm ok with my decisions even if it doesn't please or fit the parameters of others.
You are ok with yourself and that is important. I'm proud of you, this is quite an accomplishment that many around you may not realize. You have taken the time to share your journey with us and it is helping while you are healing.