HOW should i read this monologue???

Okay,I get chance to use my acting chops to help a youngster get a handle on a part! First things first.What do you know about this girl,besides her being mentally ill? This is what's called,"backstory"and,even if it's not in the text you can use it to draw on for a solid charcterization.Is she damaged in some way that caused her illness(a good bet)is it hereditary?(another good bet) is she really crazy or has she been brainwashed into thinking that she is?This is the kind of thing you would think about for any role and,even though it's only a monlogue,act it as if you were doing a full-length play.The one thing you want to avoid is,"playing crazy"you know,bulging eyes,wild mannerisms,etc. Maybe she has a tick,like twirling a wisp of her hair when she's agitated,or she tugs at her dress. Don't make her "look crazy"either,with wild hair,dirty clothes etc,in other words,avoid cliche like the plague! Follow the ellipses in the monologue where indicated and let some of the speech come out in a rush as though she's afraid her brother won't understand her.Keep it very quiet,make the audience come to you and listen carefully at what you're saying,then,Bam! At the end of the speech,she suddenly loses it(anger born of frustration is the way to go,I think) and sobs helplessly,leaning against the brother,clutching at him as if doind so will keep her from going over the edge.Do you see how modulation and under-playing will make it more compelling?Let me know how it goes after you try it with my suggestions,okay?