You're asking the wrong question because you're making the wrong assumptions. You're assuming that the only way to get the child and get the guy is to put up with the asshole. We'll leave questions of nature vs. nurture aside and I'll concede (for purposes of this argument only) that the only way to get the child is for the asshole to father it.

So really all she needs is a sperm donation. Yes, tricky how she'll get that.

As for the guy she gets at the end, she doesn't get him because she went through the asshole; she gets him because by leaving the asshole and rebuilding her life she becomes the sort of woman who's attractive to a worthwhile man. Assholes like weak women they can dominate while men worth dating are attracted to strong women, the sort of women who don't put up with that shit. Yes, the asshole was involved in shaping her into that woman, but it was discovering she had the strength to leave and defeat him that lead her to found it. If she has that foreknowledge, she doesn't need to go through the asshole, and if she doesn't then she'll simply find another asshole.

The real question is what sort of person should she be? The answer is the sort of woman who will stand up for herself and the people she loves.