Daddy issues (literally) – relationship with my dad will never heal, so how can I?

I've recently turned 40 and after four decades of the bare minimum of effort from him, it's really dawning on me that my non-existent and broken relationship with my dad (75) is never, ever going to be what I wanted or needed it to be. There's no Hollywood reconciliation coming or magically finding a way of mending things – for one, he's a covid-denying, right-wing conspiracy theorist drug addict with a decades-long victim complex, so even having a "normal" conversation has always just sucked for as long as I can remember. Entering my forties, I really want to try to make peace with this. I've been to therapy on and off over the years, but the frustration and pain I feel about this somehow never feels less raw – and somehow especially now as whatever window for hope my younger self might have had is clearly firmly shut. Is that just how it is? Would love to hear from others who have had similar struggles and how you found acceptance within yourself?

EDIT: Thank you so, so much to everyone who responded to this. There's so much great advice here and also just so much bravery and determination and compassion. I genuinely appreciate everyone who took time to share advice and to be vulnerable enough to share similar stories. I was on the verge of tears when I made this post, even more so reading through everyone's responses, but I feel so galvanised and resolute to take my healing firmly into my own hands now. Also, re-parenting, what a concept! Going to dig deeper into this because I had never considered how I could be there for me in the ways that my dad wasn't.