Hey OP, I can see that your torn over the kids, and I can see from what you have mentioned about your ex that you just so very used to putting yourself last in every single scenario. I think you have a very real fear and guilt of putting yourself first, even when that’s what’s best and it’s what you should do. I also think while you know leaving your ex was definitely the right thing to do, you carry a lot of guilt because of how it’s impacted on the children and in turn I think this only makes you pander to them even more. If it’s any consolation the children won’t make the direct connection between you trying to compensate for the guilt you feel and the change they’ve had, they will just see that they can continually push you until the can get what they want/their own way. This is not good for them or you! Also your hoping that by giving them what they want that they will be happy, and grateful. They may indeed be happy and grateful at the time, but as things are with kids, especially teens, this won’t last long at all! Soon there will be other complaints about other things, they will push for more (because that’s the nature of kids) and you’ll give in, and you’ll give in purely because they keep pushing because they’ve learned that if they push enough eventually they will get what they want.
It is ok to put yourself first, in fact it’s important that you, and here is why:
You as a working adult, the only adult NEED your own space. You need quiet and calm and rest in order to be able to look after your own mental health. This is to the benefit of the entire family who are ALL reliant on YOU to be well enough to continue working and bringing home a wage so that you can take care of and provide for everybody. They need this as much as you need this!!
On top of providing a nice warm home, food and everything else you also realised that they boys need a bit more privacy. Your not telling them it’s tough and that they have to just put up with it. You are offering them a solution by partitioning their room so they can have some extra privacy. Is it perfect, no BUT it is a lot better than the current set up, and they should be happy for any improvement and extra privacy that they get, you are the one paying for it and providing it after all. This what you can reasonably do and afford to do and they should learn to appreciate that. We can all go through life wanting or dreaming of a better house/car/holidays or whatever else but at the end of the day someone has got to work to pay for it!!! When they work themselves and are old enough to contribute to the household, that’s when they can have a proper say in things.
Children have to learn to respect the value of things and the work it takes to provide it. If they continually get everything they want, with no real effort or work to attain it, they will never respect or appreciate the things they are afforded by your hard work and dedication as a mother!! If they don’t learn this soon, life as adults is going to be very hard for them indeed!! So you see, doing what’s best for you (and you very much deserve that extension room btw) is also doing what is best for your lovely children too.