So your reasons for staying are:
my Son will be so upset.
Maybe he will, which you will have to manage, but you matter too, plus your partner isn't being a great role model for relationships is he?
I feel very sad for the boys as they have bonded well
If they are now friends, is there any reason they can't still be mates if living apart? And if not, then ditto above, not a good enough reason to stay
long term getting older I don't want to be single forever
Even you admit this is not a reason to stay in a bad relationship. It's possible to be very happy when single and definitely better than together constantly arguing and feeling miserable
There is a lot of guilt
Guilt over what? That it's not worked out? Sadness and regret is understandable, guilt is pointless and again - not a reason to stay
maybe I just don't know how to live with someone
Or maybe you can't live with this particular guy. But even if it's you, so what? You aren't happy and there is no sign it's getting better.
I don't want to feel like I'm quitting and it would easier with someone else when it might not be,
Why is deciding a relationship isn't working for you 'quitting? And why is 'quitting' a bad thing - you've given it a year fgs. Surely refusing to 'quit' is just flogging a dead horse? And you don't know if it would be just as hard with someone else, as you haven't got a comparison. Lots of people are saying it shouldn't be this hard and that's not their experience of living together.
I'm just being silly thinking it's not this difficult for everyone else.
And it's not usually this difficult, as pp's have said. Relationships can have tough patches but generally they should enhance our lives not make them worse.
Accept the inevitable, OP. Separate. You tried and it's not worked out. Move on.