My maternal grandfather was born in ~1917. My maternal grandmother was born in ~1919. They started a family early in their marriage. Though they lost one child in infancy, they eventually had five children.
When the kids were about ages 16 down to age 3, my grandmother felt overwhelmed by the responsibility. She left. She never came back.
My grandfather had to drop out of University of Michigan.
My grandmother met, dated, and married ‘exciting’ and ‘adventurous’ men – one who worked abroad, giving my grandmother the opportunity to live a ‘cosmopolitan’ life. Another played music. All pretty much either gambled, drank, or both. That appealed to my grandmother.
My grandfather struggled desperately to raise the kids, leaning inappropriately on the eldest – my mother – to assume more responsibility than she ever could have or should have. She got out as soon as she could, and in the only way she could: she married my father … far too young and immature, and under inauspicious circumstances (his father had recently committed suicide over learning of his wife’s (my other (ie, paternal) grandmother) infidelity.
As the five kids got older, they gravitated toward their mother, who – by all traditional definitions – had never been, and still wasn’t, a “mother.”
My grandmother ended up with a slightly-less-than-okay man who – after he stopped drinking for good – didn’t smack her around any more. Which … y’know … is nice, I guess.
She stayed in that marriage and predeceased her husband. She was quite dependent on her children (among other things, she had never learned to drive, and – IIRC – never had a paying job).
TL;DR: my grandmother was charismatic as hell, and whip-smart. Everybody loved her. Though each and all of her five kids would have been forgiven for having written her off for good (for leaving them all when they were just kids) and never having contact with her, they each decided that nobody won in that scenario.
These things are horrendously complicated and terribly sad (you have my sympathies on a handful of levels).
But put me with those who say you have to do what’s best for you in this situation, and what you can best live with long after your father leaves this Earth.
I wish you peace.