the enviornment for raising children is abolished

I don't see how.

Both sexes plays different roles in upbringing, and any psychology book would tell you that a lack of either will mess the kid up pretty bad

I think it is more likely to say that the lack of a balanced upbringing will result in a messed up kid, there will be nothing to say that one of the women taking on the gender role of a male and providing exactly the same upbring that a man would, would screw a kid up any more or less than actually having a man as a father. (and no I am not talking about trying to look like a man, I mean providing the same emotianal and disiplinary input a man would).

look at all of the disfunctional homes resulting from divorce.

Which is generally then a single parent family, resulting in half of the time and support a child would get from two parents regardless of gender.
Plus there is the emotional distress that a divorce places on children, which would not exist with two commited partners of any sex, so I think the divorce argument is a red herring and proves nothing either way.