Hi Y.,
You are wise to bring up this concern, and not shove it under the rug, hope it goes away, or that he outgrows it. It's important to find out if there is an organic, underlying cause for your child's behavior. The sooner you get proactive the better, because when his hormones kick in, if not sooner, he could potentially hurt someone, including himself or a pet, if he loses control.
Please get your child some professional help. If he is unable to control these temper outbursts, and your strategies have not had an impact, then a professional, objective opinion and help are indicated. The right professional (respected child psychologist/psychiatrist, and/or possibly a pediatric neuro-psychologist) will help devise a behavior plan between your child, school (counselor, teachers, etc.), home, and the father (if he's in the picture), grandparents, etc. so everyone can be on the SAME page and everyone knows what the goals are, and so your child cannot "pull the wool" over anyone's eyes when it comes to managing his anger/outbursts.
If your child is exhibiting this extreme behavior at school, you might request that he be observed in the classroom by a Behavior Specialist. This person may be reached by contacting the counselor at your school, who can contact the Special Education coordinator. If your son's behavior is interfering with his academics, they or you may request testing through Special Education. In addition, you could take him to a pediatric neuro-psychologist for private testing.
Check with your health insurance to see if they would cover these professional services (if not, you could get letters from the school professionals and/or your son's private counselor to help in this regard).
Our grandson has had temper outbursts and "emotional meltdowns" since he was a baby. The parents refused to work with us, the school, and his psychiatrist in devising a behavior plan to help him manage his behavior, with appropriate rewards and consequences. He is now 9 years old, probably overmedicated, and he literally runs the household at home (his 14 year-older sister has migraines because of the stress, screaming, and her parents will not let her lock her door to keep him from destroying things in her room). In addition, he is unable to function at his highest potential at school (because his behaviors severely interfere with learning), and we can no longer have him visit us.
I was also a single mother, with a wonderful ex, and we worked as a team to raise our daughter (there's that village again!). I went to counseling so I could become a more effective parent, and got her into counseling to manage her "anger escalation", which had been a problem since she was a baby, and it got worse after the divorce (she was 7). She went to live with her father at age 16, as I became unable to handle her manipulative behaviors. I went to visit her at Parents Day during her freshman year of college, and unfortunately witnessed another one of her outbursts (at me) in the grocery store. I then realized I had done all I could, it was up to her now, as I had always told her that behavior is a CHOICE.
Sorry if I painted a tough picture, but I have seen the other side in more situations than the ones described above if adults don't take responsibility for a child's socially-emotionally inappropriate behavior. I worked in the schools as an occupational therapist and treated some ED (emotionally disturbed) kids. Your child's behavior is a signal that something is WRONG. He is crying out for HELP. It is our job as parents, family members, and professionals to raise our children and get them professional help if they need it, early on, so they can grow up and be productive, and as happy as possible, members of society. Children depend on US to be tough and consistent with our love and consequences, so they can learn appropriate boundaries and eventually internalize these boundaries so they can manage/modulate their own behaviors appropriately.
Best of luck, and pat yourself on the back for being proactive!