How do you stop feeling guilt?

When my dad was in a nursing home the past two years, I started visiting twice a week, but went down to once a week. He was often irate and it was difficult..but mostly our visits were good. My sister said she'd only do once a week because of how he treated us in our life, mainly backing up my mom's horrible severe abuse. So I went once a week.

He was recently diagnosed with aggressive cancer, untreatabl, in January . It was heartbreaking. He's been in hospice a week now and each day he can talk less🥺 He was the only parent I could sometimes ask minor advice. And even though I've been by his side each day, telling him I love him, I get guilt still that I didn't go as often last year as I could have. 🙁 I think it's going to make me anxious after he passes. How to alleviate any of it?