Heck yes it's possible to change, Paul. If you're self aware enough to realize that you have character flaws, then you can do something about it.
There are quite a few ways to go about it, but for my money, you can't beat therapy. It is very difficult to remain objective about your life. Having a context-neutral third party assist you can be invaluable. If you are not used to opening up to people (you had mentioned coming from a family that isn't used to talking about issues), then a therapist can help you there, too. Some things are too important not to bring in a professional. If money is an issue, there are many therapists who work on a sliding scale (I managed to afford one while working in California, on minimum wage, for example).
I wish you the very best of luck. You have a son, a wife that loves you (and therefore a friend), and the awareness to know that there is something about you that you don't like and want to change. I'm positive that you can manage that change!