Okay this might be a bit long but here goes.
I went out with a guy from the age of 15-21. He was from a very wealthy family. We split on good terms. Too much too young.
I met my ex DH at age 22 married at 23 and had our Ds at 24. He's a nice guy but in hindsight I was probably on the rebound and we split when I was 27 and my son was 3.
I spent 3 years single and built up my career while raising my son. Ex DH has been great and we co parented really well. He met someone else and it was very cordial and civil. She's great with my DS and they get on well.
As luck would have it, I reconnected with my high school sweet heart when I was 30ish and we married and had twins. The twins are now 5 and my DS is 13.
As I said earlier, my DH and his family are wealthy and they treat my DS like he's their own and never see the twins get something and leave him out. My DH offered to pay for my DS to be privately educated like our DTs and I ran it by my Ex who said no which I totally understood. He's at a great school and doing well. However, my ex has asked that my DH stops being so generous to DS as he feels like he can't compete. My DH has always deferred to my Ex when it comes to any decisions regarding DS and, like was the case with the schooling, will put an offer on the table and let me and Ex decide between ourselves. He never mentions anything to Ds so he's unaware of these offers and decisions. My ex isn't happy that DH, on occasion, will buy my DS the latest trainers or football tops and clothes. He doesn't spoil him but he does treat him well. I really don't know what to do because I don't want any friction but I also don't want DS to think he's being treated differently to his half brothers.