My daughter has Sensory Processing Disorder. She is not on meds. She is in the 6th grade. She didn't want anyone to know (and still doesn't) that she is "different." Therefore, she would be able to hold everything inside to project to everyone that she was fine, everything was fine--and then she would come home every day and literally unload on us. Every little thing that had bothered her that day, every little anxiety or upset she'd felt, we would hear about. Crying, shouting, running away and hiding, pouting, tantrums--you name it, we've been through it. Not having any friends, no one wants to play with me... you get the idea. Like you, I too became emotionally exhausted from dealing with my daughter and her issues. I had to learn to shield myself from her and not let her "toxic" emotions affect me. It's her battle; not mine. Since I've learned how to shield myself, her issues and problems don't bother me much anymore.
The good news: it does get better. Trust me. If you continue to get your daughter the help she needs to learn how to cope with what she finds overwhelming, life will keep getting better.
We had our daughter see a Childhood Specialist (CS) from age 5 to 11; right now, she doesn't see anyone because our health insurance changed. I haven't bothered finding anyone new in our new network because she hasn't expressed a need or a desire to see anyone new. That might change with the teenage years, but we'll cross that bridge when we come to it.
We found an absolutely wonderful CS who prefers to work more on behavior modification than giving drugs. She was wonderful at helping my daughter find useful ideas for her to cope with situations, introduced her to keeping a journal--just for her--to write down stuff when it overwhelms her (the idea is to write it down and once it's down on paper to release it and let it go), helped mom (me) with wonderful ideas on how to help her, etc. I can't say enough about the wonderful CS we've had for the past 6 years. We've also gotten our daughter other help, like Speech and OT/PT (through the school), additional outside PT, help with weight management, etc.
I've also been watching and encouraging anything my daughter is interested in. She's been in dance class since age 4, and it's done wonders for her balance and coordination as well as working toward a goal (spring recital dance). She's not big on sports (if your daughter likes sports, that could help her run off energy/anger) but loves dance. She discovered that she likes sewing with a sewing machine this summer. She loves to read, still plays with dolls/Barbies, Monster High, Liv dolls, likes doing creative stuff. We're working on finding other interests as well.
The biggest area we work on is social/friends. My daughter really struggles in this area. It's so much better than it was in daycare, but she still has a hard time and it hurts my heart to see it. But I'm building her up to believe and love herself, to trust in herself, to rely on herself. I told her people will gravitate to you when they see that you like yourself and you have a pure heart. She has so much empathy, I wish more people had as much as she does. I'm also teaching her not to let people walk all over her too, because that is also a problem.
Find the tools your daughter needs and get her all the help you possibly can right now. It will pay off.
And for what it's worth, I DO NOT believe in pharmaceutical drugs. I believe they have the potential to create a lot more problems with their side effects than what they purport to help solve. If you are feeling overwhelmed with your daughter's anger, take her to see a naturopathic doctor and have her tested for heavy metals. My daughter tested SEVERE for heavy metal toxicology, and we chelated about 3-4 times. Getting rid of the heavy metals in her system also helped in calming her down and getting rid of the anger. We also went to an organic lifestyle when she was seven and cut gluten, cow dairy, and soy out of our diet. Dietary changes also helped enormously.