DH ex has been nothing but a nightmare for the whole 4 years we've been married, never worked a day in her life cause she's depressed and has had another child, she's 43, so she doesn't have to work (her words not mine)
Basically we have been paying £30per week maintenance for my husbands son and she's decided it's not enough as she has 2 kids now (one isn't anything to do with us) and has reported us to CMS, The ex text me before Xmas asking for our address as SS wanted to send us a card, we were over the moon and thought we'd reached a turning point. What turned up was the CMA papers 
we've received a letter telling us that she is not entitled to anything at all as my earnings aren't taken in to account only DH. And I'm the high earner.
What makes it worse is we aren't allowed to see SS, he won't answer the phone we bought him (he's 9) he lives 2hrs away and his mum has poisoned him against us and has no intention of letting us have any contact.
She has blocked all contact with us and We have stopped all money AIBU?
I've decided instead to put the money in a separate bank account for SS when he's older.
He won't come to our house because we make him eat his dinner (all he has at home is macdonalds and pot noodles) and he's not allowed to stay up until 1am playing on fortnite.
No negative comments please just not sure if I'm going about it the right way.