im not a teacher but I am a certified nursing assistant and we have patients at times really difficult to take care of...

you are describing when do you know you are burnt out...Well here are some symptoms....if you wake up every morning not wanting to go to work....if you start getting angry at everything....and also especailly if you accidently lash out or speak in a way that may be harmful to the kids ....you say that would never happen but people have limits and buttons and when those are exceeded and pushed beyond max youd be amazed at what we do....Perhaps you could talk to the head people above you and say Listen this is what I have observed from this student....this is how he acts.....this is how he reacts....It is from my standpoint that I believe he should be in the program for aggressive children...show them your case....provide examples.....and tell them frequently.....lets say the student left and you have all the kids in the room that you had before....would you want to leave the next day and never come back...i know i have felt that way when I go to work...today in fact....but it is just stress....I can deal with stress ....tommrow it will be something new....thats life ...thats a job....but step back see how life altering this is....the reason I dont quit my job is because I love it...im stressed to the max at the moment....I get angry when I get home ...but I love my job...you have to really think about it. Ask the school district about other job positions available...if they offer you something else do the pros and cons....do the evaluating....im sorry I didnt give you a direct answer but i cant give you an answer only things to think about when you feel this way. You know your body and your mind and I promise you you will know when it is done with it....good luck