Sorry *hugs*

IF he was difficult during the time you knew him and got progressively worse as he got older, it's no wonder you feel conflicted on his passing.

I think we all crave love and acceptance from our parental figures and when it feels withheld or denied that can lead to feelings of guilt.
Especially if the circumstances didn't allow for the possibility of reconciliation before they pass.

Like all feelings of grief I'm sure it will lessen with time.

I’m sorry for your loss.

There’s no right or wrong way to feel. Grief is a very individual experience, whatever you feel is just a part of your unique journey.