HiVimto,
just wanted to say that I completely understand where you are coming from, it can be really difficult trying to do the best thing for everyone. But in imho you dh is out of order, I don't think you are trying to push his chidren away, you are just asking them not to say overnight for a month. You're not saying they can't come round at all, just a little bit less for a month.
I feel completely frusatrated on your behalf as it sounds like you dh's ex decides to go away and you have the children . You are not at her beck and call, The visits from you ss should be planned and at regular intervals, not when she fancies going away. You need to start to be assertive with your dh.
I also understand how unomfortable you might feel when trying to establish breast feeding and recovering from birth with people other then your dh around.
what made me very cross was your ss balancing a dvd over the babies head and on the moses basket, wtf, he's 14 not 4. I understand that he may feel left out but this is no way to behave.
As you might be able to tell, I've been in the same type of situation.
Due to a fall out with his mum, ss came to live with us just after ds was born, very small house, only one living area, and I have to say I spent alot of time sitting upstairs. Ds was tongue tyed, so couldn't breast feed, so spent every 2 hours expressing. Felt like a heffer as it was, didn't want an a teenage audience to go along with it. so I completety understand how you feel. SS was also very clingy to Dad and wouldn't leave him alone. I mean I would be upstairs pumping with the door closed, dp would come in to see how I was and within mins ss would be outside the door asking for something.
The only thing that I can suggest is this,
Don't tell ss off, let dh do it. If he is holding a dvd over ds's face move ds. Don't leave ss with ds at all.
Try to have clear routines set in place as to when children are visiting and for how long.
have clear expectations that you are not tidying up after them, or cooking and cleaning up. They are old enought to do that themselves.
Also don't worry about what their mum is thinking, don't care if ss tell her you haven't washed for days and are still in your pj's, she's not an important part of your life (fcuk her)
hope things get better for you, which they will in the end.