Trying not to stress has gone horribly wrong....

I am currently 8 months pregnant trying to maintain a heathly blood pressure. I did an Ancestry.com test a few months ago because I was curious about my backround. I've never met anyone on my mom's side of the family so that was the main reason I wanted to do the test. My dad's side is about 99% Russian Jews so I was also testing to see if we were Ashkenazi. Long story short my dad and his dad also took the test and I've just unearthed that he is not my father! 32 years old and the man I grew up with knowing as my dad isn't. My mother isn't a very honest person and was a night club singer back in the day so after the initial shock I've realized this was something I should of thought about. When I asked her about this ( calmly and not accused her of any wrong doings ) she went off on me! She said I'm going to ruin her reputation and my father fudged the test to make her look bad. I really want anwsers and to fix things with my mother because I'm heart broken and she keeps making it about her. I don't know where to go from here. She is making me doubt what I've come to realize is the truth. She will not have a nondefensive conversation about it with me and just the other day blurts out nonchalantly " maybe I was raped". I know this was long but please I need some advice. My mother and I 's relationship has always been strained but this might be the straw that breaks the camels back. I love my mom but fear she can't be honest or I will never get anwsers. Even if she honestly doesn't know who my father is she won't say that!! Help!!