It must help him if you show him that you can calm yourself down and how he can calm himself down. What are his violent rages about? He must be angry about something. I think one of the greatest gifts you can give him is to teach him empathy, in the sense that most people don't learn it until they're much older, he needs it at a young age.
I don't have kids, but I 100% swear by Supernanny (Jo Frost). I'm sure I've mentioned her before. Check out any of her books or TV shows.
It seems all you can do is to keep challenging and correcting his behaviour.
It must be hard on you to have no family members to lean on. Most mothers have people around to help, as your article link says. But I think you need to be happy so that he can learn to be happy, as a way to overcome life's difficulties. You need to be the exact role model of who you want him to be as an adult [the logic of someone who doesn't have kids].
It seems that maybe he's evolved this way of dealing with his hard feelings, which like you say he seems to have learned from his dad. The Buddhist way would be to apply antidotes, in the form of opposite feelings: calm and compassion. He's a bit young for all that probably. But see if you can work that idea in, it really works in my experience. Jo Frost would sit him down and ask him why he gets angry and various questions. Unfortunately I'm not an expert like her so you'll have to go to her programmes / books.
The Western way is education, the Eastern is insight, and they make a powerful combination. Educating him to behave a different way, insight into the reasons why he behaves the way he does (which admittedly was put in place at a very young age).
Do you have any close friends you feel would make good role modes?
If so, try asking them to talk with him occasionally
I promise you, she's a child rearing genius. She sees difficult aggressive children every day. I urge you to check out some of her stuff.
I watched one of her episodes. It was really good :) I actually already do a lot of what she said, but it was a great comfort to see that maybe I am actually on track. I realized that some of the times he tests me is when I'm usually tired....he can sense when mama's had a bad day.
One of the things she did in this episode is exactly what I do with my son. In the example they were girls....so it was princesses and castles. My son chose shapes. We play a lot of games together, like card games, chess, connect 4, stratego, etc...(yes my 5 year old plays a mean chess game, lol!)....so my son chose shapes for his chart.
So I have a chart on the wall I made, laminated, and it has pictures of the morning routine, bedroom routine, play time, and a weekend schedule. So he always knows what to expect. When he does what he needs to do, he gets a shape in a jar, (cut out kind of big) like a heart, or a diamond, or a spade, etc...and when the jar is full, he gets a prize or a special unknown outing of some kind. I have a case manager that supplies me with tickets to local events, movies, etc, or toys. I have a "stash" put away that he doesn't know about that we got donated, and so I don't have to run to the store for rewards, I have them already....I was worried that this will make him materialistic. I think that may be the problem I faced when his friend won the raffle basket. I don't want him learning that we do things to get something in return. I want him to know we do good things because it's the right thing to do...so....I constantly remind him, and sometimes I try to make the reward simply going to the park and I make sure to have meaningful conversation with him between ball tosses, or rock climbing, lol....
One thing I hadn't thought of that the super nanny did that was brilliant was having one for chores too...I think it's time he had some chores because he is old enough. We cook together and he usually always volunteers to do the dishes, lol....He never has to be bribed to help around the house, but I think it would be nice to start a designated chore chart for a little more structure around it.
I also thought of some tips for a friend of mine who is struggling with 3 kids...also totally alone...It's hard to know what's "normal"......so to see and hear a different perspective is very very helpful. Thanks friend :)