That's a horrible lesson for a child, though. It's not a positive at all.
And you've presumed that grandparents would want to be involved, and they may not. Hell, my sons grandparents aren't involved and me and their son are very happily married with no drama. They just decided they didn't want to be grandparents.
There may not be stories, or grandparents, or history, because he may well (very reasonably) be pissed off that she got pregnant deliberately against his will, and he may then decide not to have anything to do with her or the child. Knowing "who" your Dad is won't help much if you also have to accept that he ditched you because of your mum's actions.
35 isn't the ideal time to be starting again, no. But that's why the impetus is on OP to decide what she wants, and stop waiting around for it from this man. It's not happening. It's a straight choice here, him or a potential child.
And after that, a potential child from a new-ish relationship; with the risk that 18 months to meet someone and get to know them may impact on fertility, or a sperm donor; like you said.
But presenting getting yourself accidentally pregnant as being in the best interests of the child is insane.
I'm a foster kid. There's loads of us without standard parents. Being rejected/abandoned by a parent isn't the type of pain that would be lessened by Mum having 100s of photos with him before you were born and knowing some of his life stories. It'd just make it feel more like you were the problem.