I absolutely believe her! She doesn't give a crap what people think, so I don't know why she would lie. People just don't believe her because it's her and they think she just wants attention. It's reasons like this that victims of sexual abuse won't tell anyone because they'll be judged and risk people not believing them. Also, here is her post on Instagram where she went into more detail about her sexual abuse experience.

"I was sexually abused and physically growing up from the day I can remember till I was 14..when I finally had the courage to lock my door at night and sit by it. All damn night. Waiting for someone to take advantage of my life again. Over and over I waited for it to stop and finally it did. But some of us aren't as lucky to get out alive. Please today stand up for every soul Mistreated. #timesup"

And here is her tweet about it:

"I never knew what was right or wrong growing up.. I didn't know the person sneaking into my bed room at night was a bad person. #timesup"

Absolutely! I don't understand why anyone wouldn't believe her (unless they were a mindless and pathetic hater, which Bella seems to have a lot of). Like you said, people just don't believe Bella because she's Bella and will think she just wants attention. It's really ridiculous and pathetic.