I really don't know where to start so I guess I'll just jump right in.

My son is 11 and has ADHD. He has always done pretty well in school up until this year. At the beginning of this school year one kid in his class apparently decided that it would be fun to pick on/bully my son. We tried for a month to get our son to just ignore the kid, in the hopes that the kid would get tired of getting no reaction and leave him alone. When that didn't work, I contacted his teacher and made her aware of what was going on. Many times I contacted her about this issue. Finally one day, after my son came home in tears with a discipline report, I went to the school to find out why, after as many times as I had contacted the teacher, my son was being written up. I found out that my son had not been doing like we had asked (of course it was kinda retarded of us to think that with our son's ADHD and being as sensitive as he is,(he bawled his eyes out over the movie The Green MIle, he cries over the Feed the Children commercials, and even animated movies that feature the loss of a character makes him sad to the point of tears) that he would be able to just ignore this kid. The two had been going back and forth, kind of a tit for tat kinda thing. The school tried to tell me that my son was seeking this other kid out, and I told them, he's only seeking this kid out AFTER he has done something to him. I did get on our son about not doing like we asked of him and replying and responding to this kid. I'm all about fairness, if my son is involved in wrongdoing, then he should have to tow the line. Our son has never really had any trouble at school with other children. But this year, all the sudden like, the principal and vice principal are trying to tell me that this has been a pattern all along. My question to them was, then why wasn't I told about this "pattern" before. None of his other teachers ever told me that my son was bullying other students, only that he would get frustrated with his work and at times would growl a bit or ball up his fists and stomp his foot. Never was I told, "Hey we got a problem, we think your kid might be developing into a bully."
I have always bent over backwards to try to help the school help my son. Unless I had a "gut feeling" about a particular thing they wanted to implement on his IEP, I pretty much deferred to their training and "expertise". I have always been one to try to work with the school as much as possible, up until now.
A week ago, my sons bully decided to up the ante with sexual insults (as if 4 eyes, cock eye, retard, and "are you pregnant?When are you having the baby??" (our son has a little belly, but is far from being overweight) wasn't enough.) He told our son that he did him a favor, that our son is here because he had sex with his mother! This is truly appalling. That is the kind of language you expect to hear out of adults, not fifth grade kids. We had just moved back into our house after a house fire in October and our water had not been finished, so I was waiting for the plumber to bring his happy hiney out and fix it so I could shower and go to school and again discuss this issue without smelling like an overworked mule. The plumber took his sweet time and it wasn't until 4 days later he showed up.
Unfortunately my husband, who normally stays out of things dealing with school (he had many bad run in's as a kid with really bad teachers and horrible counselors so his opinion of them is not very high so he has stayed out of things and let me handle them my own way) decided that enough was enough and went to the school after picking up our daughter at middle school to talk to them and let them know what was said. When he told my son to tell them what was said, our son started to tell the principal and vice principal, the vice principal cut him off without letting him finish and said "Well what did YOU do first?" At that my husband said that is enough we are done and told our son to get up that they were leaving. The principal jumped up and told our son to sit down. My husband promptly told her she was not to tell his son what to do after he had given him a clear command. She proceeded to step to him, getting in his face as much as her short self could (considering my husband is 6ft tall). He told her to get out of his face and she came back with a retarded answer of "How tall are you?" He told her and she said "Well how can I be in your face?" and he promptly told her to keep her psyco babble to herself that she knew damn well what he was talking about. Both the principal and the vice principal continued to be rude to him so he flat out told her "Bitch you don't run nothing but your mouth and this office and we are leaving."
Of course after he came home with our kids, it wasn't long before the police arrived at our home to talk to my husband. They went back to the school and then returned with the Chief Security officer and 3 car loads of police to give him a letter letting him know he could no longer come on the elementary school or middle school campus. Which that is the least of our concerns. I went to the school myself to let them know that this is ridiculous and that all we want is fairness in this matter. If you want to claim it is a tit for tat kind of issue, then punish them BOTH, not just one. If they won't leave each other alone and it is a mutual kinda thing, make them BOTH tow the line. Like I told them, I know you can't tell me what kind of punishment, if any, you meet out to the other student, but at least if I know you are implementing this kind of deal, that at least I will know that my son isn't being held as being totally responsible for this fiasco and being the only one to be made to tow the line. I was told that they would pull both kids out of class together and if it took all day to hash it out and come to some sort of agreement that it would be resolved.
Well they pulled them out of class Friday, after some talking, and the boy claiming that his sexual comment was really "I did your mom a favor and made you a sandwich." (which apparently they believed that bald faced lie) they sent the kid back to class. The worst part was this....They had 4 ADULTS sitting in the room with my son telling him HE was the problem, that he acts just like his dad, and that HE was the bully!!!!! I don't know about you guys, but I don't know of too many bullies that come home crying.about being picked on. Maybe they do, I don't know, all my experiences with bullies as a kid was from the perspective of being the one being bullied and abused. Because of that I REALLY have issues with bullys and bullying. My son knows how I feel about the issue of bullying and knows that if I think for one second he is responsible for being a part of bullying, that punishments will be handed out. I don't tolerate bullying period.
I am at a loss as to what to do, what our rights are, I've been trying to read up on the laws and policies, but most subjects I find deal exclusively with bullying or when it comes to the subject of special education and special needs kids that the only thing I could find was subjects deal with rights to education.
I feel like my son's school has failed him completely and has decided to place the blame on him, for whatever reason. I don't know what to do, I don't know if we have a basis for a lawsuit. I have written letters to several lawyers and advocacy groups to try to find out what we can do.

Well that is our story, sorry it was so long. I would appreciate any feedback, we are at a total loss.