Nikki80:
I know how you feel. Every second of being away from your kid feels like an eternity. I know the drill. I've been there, done that. There is no easy way of explaining to those who are not in our situation on "why your son is not with you". Let's put it in perspective, every OFW's situation is different, unique. some examples are: both parents have the same 9-5 jobs, you can never trust a stranger (nanny) to watch over your kid, influence in schools is very high specially in a big city where gangs is a normal way of life, just too risky. In that scenario, the next best option is to let the grandparents watch over the kid temporarily until such a time that you can bring him over to where you're at.
We also have an 8 year old son. We also left him with his grandparents since he was less than a year old. BUT as parents, we see to it that we communicate with him EVERYDAY thru skype for the past 8 years. Before we leave for work, we see to it that we communicate with him at least 30 mins to an hour during business days and at least an hour or two on weekends. Ask him about his assignments daily and sometimes helping him accomplish it. There are a lot of online games that you guys can play together if you really want to spend some quality time with him while you're both online. I also make it a point to come home every year so we can spend quality family time. And in those visits I see to it that I meet with his class adviser and some of his teachers every single time so communication lines would be open in cases like there are emergencies or special situations (like what you're in) will be prevented.
But that's just me.
I know that what we're doing is still inadequate and would still be considered as "poor parenting" but that's a choice that we should live by whatever the consequences. All we can do is cover all the bases since we are not at his side always. But things will get better sooner rather than later for my kid. And I already made him that promise of which I am not planning to break.
In your situation, accept the fact that there's nothing more you can do about it. Transferring him to his grandparents (mother's side) would be the best thing to do FOR NOW. And if you're mind's already made-up then do it NOW, not tomorrow, next week or next month. DO IT NOW so he could enroll and transfer to another school while he still can. While there is still time.
You've been working for your company for awhile now so I think they can understand your situation (and allow you to come home again) specially when it involves the welfare of your kid. Have your in-laws research their area if a school would allow exams (evaluation exams? I'm not sure...) so you're kid would be enrolled in his supposed grade (grade 6?) in the coming school year. Have them look around and ask if it's possible.
As far as your parents (mom and step dad) is concerned, they can't do anything about it. They already had their chance and they blew it. BLEW IT BIG TIME!!! Please accept the fact that by moving your kid to your in-laws, bridges will be broken, feelings will be hurt and bad-blood would develop between you and your parents as well as your parents and their in-laws. That's a given and I hope you've thought about that situation really hard.
BUT who cares
Your son is the victim here. Not your parents. Stick it to them and let them know how disappointed you are at them.
Last but not least, don't blame yourself. WE are just regular parents trying to make a bright future for our children. There's nothing wrong with that. All I can say is: "Bad things happen to good people". Keep your chin up. Learn from your mistake. You're both good parents.
Talk to your kid and apologize to him for your shortcomings. Tell him that you'll try your best not to be complacent and be more involved with his life on a daily basis. Tell him truthfully about the situation, when you'll both be back for good or when will he be able to join you.
And if you make a promise, keep it.