second pregnancy

Hello, I'm new and struggling so wanted to post, wondering if anyone might be able to say something that helps shift my thinking and how I feel.

I have a gorgeous little nephew with ASD, undiagnosed at present but after having worked with children alot and having my own, I can see that a diagnosis is just a matter of time; I can also see that mainstream school will never be a good match for him.  That we have no idea how much level of care and what help he will need into adulthood yet. 

My brother has announced they are expecting a second and I feel pretty angry about this; I feel they have no idea what their first borns needs will be yet, but I can see it is going to be anything but easy, fighting for help and services and dealing with his frustrations.  It feels selfish and reckless, not an adult decision.  They recieved no genetic counselling, just jumped straight in.  

I know I need to respect my brothers choices here but I am worried this second born, which is a boy, will be more severley affected.  I also feel concerned because the mother has a severe mental health problem. 

I love spending time with my nephew and he gives us all a lot of joy, but it is really hard work for very little if anything back in the way of interaction, I am worried he will always struggle to make friends, at the moment this is completely unimportant to him. 

I also feel they have no real idea of the increased level of support they are going to need from a family of 3 to a 4 and as he grows, like they haven't considered this at all. 

Sorry in advance if my email offends anyone, as this is not my intention, I'd really just like to feel better about this and thought this may a good place for me to work through it.  Ive been sitting on this for a while now and I don't like feeling this way. Thanks