Brother SPN,
I can asure you that the Roman church teaches no such thing. Rape is rape according to the catechism, a violation of a woman's dignity and a mortal sin imperiling the salvation of the perpetrator, whether she gets pregnant from it or not. I have never heard of this and I know of no trace of it in recorded history of official ecclesial documents.
That bit about the heat drawing the seed is related more to how the female orgasm causes the cervix to draw the semen farther in, which is simply Hildegard's biological description. It comes from one of her treatises on biology.
I actually think that you have taken an innocent remark from a 12th century nun on human biology as she understood it through her scientific investigations into the role played by the cervix in the sexual act (an act of "love" as she saw it between husband and wife and not a rape!), and have placed upon it an interpretation which has nothing to do with it regarding an alleged church understanding that rape would not be rape if the woman becomes pregnant.
Its not talking about rape in any way nor is it making some kind of apologetic for it. If you read up on any scholars who have wrote on this passage they will explain the biological point that Hildegard was making about the brain's activity during sexual arousal and the cervix.
I am greatly surprised to read such an allegation from you, although if something did occur on a personal level as you say then I am appalled but do not attribute it to catholic teaching. I should add that I firmly take you at your word and believe you, however I cannot say otherwise than that it is not catholic teaching.
There are great cultural problems for example in Italy, which has a well-known culture of silence when it comes to women who suffer from abuse due to the excessively masculine orientation of society but this is no more 'catholic' than the Punjab is authentically 'sikh'.
