Maybe this particular school environment isn't the right "fit" for your son.
I would do some research of other schools in your area - maybe a smaller school, a Charter type school ? Charter schools often have smaller class sizes, and will have different learning styles (like more hands-on activities).
Not all kids fit in the typical classroom setting, and I think exploring your school options would be a good idea.
I urge you to talk to your son's pediatrician about his behaviors.
These types of outbursts do not just 'go away' - your son needs help, and he needs you to help him get it.
I'm sure he doesn't understand why he is acting out, its probably very scary for him. As your son gets older and older, his violence will most likely increase, so getting a hold on what is going on now, is imperative.
The pediatrician is a good place to start, then he may refer you to a Child Psychologist for evaluation.
In my opinion, this little 9-year old has had a chaotic few years of her life. Parents splitting up, mom remarries, has a step-father, gets molested, doesn't see Dad regularly - and frankly who knows what else has happened at her mom's house......
I would highly, highly suggest this young girl get into some good counseling with a professional who is smart and understands young girls who have experienced trauma - not your "run of the mill counselor", but a Child Psychologist who specifically works with young children.
When I hear situations like these, it reminds me of my youngest daughter.
The very best information I can offer you is to find a smart, qualified Child Psychologist and/or Child Psychiatrist to do a thorough evaluation on her. Mind you, a thorough evaluation should not just be done in one visit, but over a course of a few visits, with a ton of paper work for you and her teachers to fill out.
Know what is behind your daughters behaviors is extremely important, and it is most likely more complex than just reading books and parenting.
I'm sure your daughter is not happy with the way she is, but doesn't know how to change - probably doesn't know what is driving her mood / behaviors.
But as I mentioned above, a top notch Dr. is key here!
Oh that's too bad the appointment didn't go as you had hoped.
As a Mom of a daughter who struggles with mental health issues, I know how important it is to find the right Dr. and proper help - and unfortunately its a lot of hard work !!!
I think you are wise to trust your instincts that something is going on........it makes it even more difficult when your husband isn't exactly on the same page as you, but don't give up.
Something I found helpful is journaling. Every day or evening, I would write down the date, and what (if anything) happened with your daughter. It doesn't have to be a big paragraph, just a blurb about the day - like:
Sarah took gum out of my purse, and when I asked her about it acted like she didn't know what I was talking about and swore she didn't take it. She was in a good mood all day!
I find writing down events over time, establishes a pattern and is helpful when talking to Dr.s about her behavior.
I will also paste some links for you to explore, and if you want, you can write back with your City and State, and I can try to find some local resources too.
I think it would be a good idea to look into a professional to evaluate your daughter.
My youngest daughter is diagnosed with a mood disorder, which at age 7, sounded a lot like your daughter. NO amount of discipline, charts, threats worked and our family life was suffering terribly - so was my daughter.
I am not saying your daughter has a mood disorder, but I think it would be in everyone's best interest to find either a Child Psychologist or Child Psychiatrist to do a full, intensive evaluation to get to the root of her behaviors.
I will paste some links for you to explore, and if you have any further questions or concerns, please write back.