Hey GFI... I am sorry to hear what happened...seemed to me that perhaps she was upset at the reality of your sitch, of S or D.. that she doesnt get to spend all day with her son.. and it may be a bit of guilt too.. and it coming out all wrong? So she lashed out? I'm just saying, without asking her (its an option, if you really are 'done') then, you dont know..
But, ironically, maybe if you make yourself less available and go out for dates.. she may realise she is losing you and it might make her think..?