Medical benefits aren’t a reason I have come across very many times. I’m sure that being in this situation is difficult and I don’t know what I would do if I was in the same position. If this woman knew the reasons why you were marrying her and she is okay with it then at least she knew what she was getting into.
It seems like this marriage was done for practical reasons rather than anything emotional. I just hope that no one ends up regretting it later in life. After time passes things can look very different. Then again it has been eight years so maybe everything will be okay.