Sarcastically smiling

"You cannot convict someone without any evidence." This are the exact words my mother said to me when I commented that I was procesing and trying to understand that she wouldn't have any resentment, doubt or misstrust towards my abuser aka eldest brother. I told her about it 12 years after it happened and it's not like I don't present any of the symptoms of a sexual abuse survivor. I'm depresive to the point of suicidal, anxious to the point of cutting my skin to find release, scared to death of my eldest brother and always have been. 

[I recall one event when I was left at home with my siblings, two elder brothers and one younger. My eldest brother got upset at me over something stupid and I ran to hide in my bedroom to cry (as usual). He came banging on the door so hard he almost nocked it down, eventually gave up and left. The second I got the chance I snuck out and phoned my parents begging them to come home because I was afraid he was going to do hurt me. Later on my mom sat us down and we had a heartfelt conversation about how he would never do anything to hurt me. This was a grand total of under a year after he molested me]

My mother claims it to be possible, she even claims to believe me; yet she won't "convict" him of having molested me. You can't both believe me and yet not believe me. She says we need to talk about it all four of us (include my father who will undoubtedly like every time before take my brothers side). What would that do? Force my brother to accept that it happened? Not a fat chance of a snowball in hell of that happening. Discredit my story? Sure go ahead, you ignored my suicidal tendencies for years no harm done I just have to be on heavy meds and barely function as a human being. 

What evidence could I possibly present after burying this shit inside me for 12 years. Tell me?