Sorry to hear of all of this. And sorry that you were treated like that by your brother. I don't blame you for what you are going through, and I can't fathom that anyone else would either, except, y'know, it happens all the time. 'Blame the victim'. It's easier for people to do that than to take a look at themselves and the failing systems.
I agree with what your tutor said. It's really hard to focus on stuff like college, and making a decision about what direction you want to go in academically, when you are still being so triggered and having flashbacks like you are. It's not that you're a failure. And I could tell you this till I'm blue in the face and I know that when people tell me I don't always believe them...but, you DO NOT deserve what people tell you about yourself and you ARE NOT what they say. They aren't even speaking to a person when they say those things. They are completely disconnected from themselves and they do not have all of the information.
Have you thought about checking out the PTSD section of the forums, if you haven't already? It sounds like you could really use some support with this. Also I see that you posted this quite some time ago. Are there any improvements? Have you managed to find any natural supplements to facilitate healing? I know that St Johns Wort can react with a lot of things, and in fact has to be taken carefully even on its own. So that would be something to check in about with a doctor.
It would be nice to hear from you and see how you're doing.