ual abuse in the family- difficult situation?

When I was 12 my stepfather started abusing me ually and my mother did not know about it because most of the time she was either drunk or whoring around with other guys. After the first time it happened I collected biological evidence via a tampon (He didnt use a condom) and I have kept it stored away now for 5 years, 2 months, and 23 days. The abuse went on for 7 months and I attempted suicide 3 times and have PTSD because of it. My question is: Should I ever tell my mom about this? Before you answer consider the following: She has another daughter with him (12) and they will lose their home and livelihood (I dont live with them anymore, my mom kicked me out 4 years ago) My mom might not believe me and even if she does she will surely hate me for destroying her family. What should I do?!?! I have been battling with this since the day it happened and now I have found this handy site so I thought I might pose the question here.