Before you even think about marrying this woman, you need to have two clear conversations:

1. Does she or does she not want children?
2. Is she ever going to stand up to/break away from her creepy sexual assault-enabling parents?

In the case of the former, if she decides she doesn't want kids and you do, that is gonna be a big problem. A couple having vastly different life goals is going to cause problems, no matter how much you care for each other.

In the case of the latter, she sounds very sheltered and controlled by these parents of hers who, as this situation shows, are toxic to the point of encouraging their daughter's partner to stealth her in order to forcibly get her pregnant. Is your girlfriend able to see how fucked up these people are, and is she going to do anything about it? Because if not, you'll be marrying into a family of sexual assault apologists.