Honestly OP - you either want a relationship with your father - warts, wife & all - or you don't. Either is fine, but if you don't like him very much, let it go & move on.
My XFIL was a very charming elderly gent when I met him. He had, however, been a bit of a shit as a husband (serial cheat) & father (feckless).
He eventually, after huge dramas, settled down very happily with wife #3, after causing huge embuggerance to wives #1 & #2 & their children.
For the 5dc he'd had in his first two marriages, opinions varied. 2 were very amicable with wife#3 & have an ongoing relationship with her, 1 was absolutely determined to have fuck all to do with her & caused huge family rows about it, & 2 were polite enough to her at family events but have very pointedly had nothing to do with her since XFIL died.
XFIL has been dead for a decade now, & no one cares who fell out with whom. 2 of his dc are friendly with his widow & 3 are not. I was married to one of the friendly dc & vaguely keep in touch with her on SM as she's interested in my own dc's doings.
I do know that the 1dc who made rowing with the guy's wife, to whom he was very contentedly married, a huge focus - well, they missed out on time with their (admittedly flawed) df.
Go no contact with your dad because he was a terrible dad, if you want to. But his wife is not going anywhere. So you either accept that or don't - you aren't in a position to fling ultimatums, & your siblings are not answerable to you either.