De nada mi amor!
I've lived abroad, well both before 'H', in Brazil, and when H and DS in his country Egypt. When stuff happens, it's the loneliest place on earth; anywhere that is not HOME.
OK, a smidgeon of tough love now.
If it quacks like a duck. It's a duck. 
If your H, does naff all pretty much, lives a good life, thanks to you and your working all the hours, and the minute your back is turned, shags some 'supplier', yes it DOES make him look really, really bad. He needs to work his culo off to win back your respect, to stop sinking and start swimming. Until such time as he has re-gained your respect and earned your trust, what is he if not some kind of gigolo? Have you let the anger out at him, or are you trying to bottle it up? He needs to feel you wrath somehow.
I think that somehow, you have to look past all of this, and formalise in your mind what YOU want to get out of this. Where you want to be, how you want to feel and live. What you want FOR YOURSELF AND YOUR FAMILY: Self respect, self love, a feeling of confidence in yourself and your choices. You need to be proud of your life. Talking Heads 'Once in a Lifetime' used to run on a loop in my head at times in Alex. this is not my beautiful house, this is not my beautiful life....
If you give him the shot across the bows he needs right now, and then HOLD YOUR NERVE, you can potentially have all that you need, love and desire.
Either WITH him or by yourself or with a better man. You are allowed to be happy second time around!
He has clearly had few boundaries. You need to set them in CONCRETE and now.
If he genuinely can't be a decent, loyal trustworthy man, one that gives his word and sticks to it, tbh you have pretty much no chance of getting through this. You will lose all respect for him (and it seems like there is very little left as it is)
Once that is gone, in creeps contempt, and there isn't a thing that will rid you of that. Take it from me.
if you set him straight now and he rises to the challenge, great, wonderful. If not, you can cut your losses, live where and how YOU want, doing the best for YOUR DS going forward and all will be better.
My 'H' went home to Egypt at the end of February. He didn't cheat though, he abused me. verbally mostly, but physically too. In short after 6 years of being together in London, he went native the minute he went home. We were there 3 years. I hoped he'd become the person I had fallen in love with when we were back home here. Turns out that person never really existed. Turns out I never knew him at all.
My DS (5) is also an only son (again not by choice) I would never, ever have educated him in Egypt. He needs to be educated so that he can compete on an international level, the British School in Alex, as far as I know is full of namby spoilt local mummas brats, or expats living some illusion of a dream. an education there would have crippled him.
I don't know exactly where you are, nor do I recall how old your DS is, but tbh, you need to take a much more serious view about his future. Hippy Dippy may be a great deal of fun for now, but may not serve him well, especially if he will be the only family you/DH have as you approach old age. Mercenary, perhaps, but life is hard enough.
Your family can be dealt with. I understand they can say stuff that will hurt. They may even have a point. Your H doesn't deserve any loyalty from them, and in fact if you were to put him in front of them for the bollocking he bloody well needs, it might get it into his head the betrayal he has perpetrated against you. You can put your family in it's place, you are old enough and entitled enough to say Oy, that is the father of my son you are talking about, he may have done wrong, and we may be having things hard, but it's my business to sort.
My family haven't said anything to me, but then again, they weren't really here for me either. My dad is my dad, off with his OW/DW, playing at a decent life, one where his children don't exist, and my mum and her H went down under for 4 weeks, booked for 3days after he would have left. She didn't even tell me she was thinking about going, so I know she did it to avoid picking up any pieces.
I know how lonely you must feel, and I have been there, so you know where you can find me if you need a chat, a laugh or a vent.
Don't forget too that there is always someone here on MN, we all wish the best for you and hope that you can find some clarity, peace of mind and serenity.